|“||I still love that lonely little girl I met so long ago.||”|
–Kouta, confessing his feelings in the final anime episode
When he was somewhere between the ages of 10-12, Kouta; his sister Kanae and their father traveled to Kamakura in the Kanagawa Prefecture to spend the summer with his cousin Yuka and her mother. It is unknown who the siblings' mother was, and whether this was the cousins' first meeting is also unknown.
Some time after his arrival, Kouta decided to walk around the Tanzawa mountains around Kamakura. While in the mountains, he encountered a mysterious horned girl after she had buried a puppy she had cared for and then lost to bullying children. Noticing the small horns on her head, Kouta, unlike the children of the orphanage, was ecstatic over her unusual appearance, finding the horns "awesome." He quickly offered her his friendship, but she showed distrust and reluctance towards him, Kouta not knowing of just how much she'd been deceived and hurt by Humans before meeting him. A persistent Kouta made a promise that he would come back to the same patch of wilderness the next day, at the same time.
Unfortunately, Kouta wasn't able to fulfill his promise; his father wouldn't let him outside because of the recent murder of a group of orphans in the area. Some time later, he was able to sneak outside to meet the girl (whose name he never learned at this time). He arrived to find her having waited for him in the rain the whole time. Remembering the girl's distaste for the attention the horns brought her, Kouta presented her with a wool hat to cover them up. They agreed to meet up and play together the next day. To Kouta, this was a mere friendship with someone he saw as exciting and different. To the girl who would one day be called Lucy, it was an alien and exhilarating experience, and one whose ups and downs for which she was terribly unprepared.
Again, due to the recent, unexplained homicides (by now, Lucy was killing entire families in their homes), Kouta's father refused to allow him outside. Three days later, on the last full day of their holiday, Kouta begged his father to let him go out to meet his friend. Kouta was finally allowed to leave, taking into account the lack of murders since the ones that initially kept him inside.
Kouta went to the usual place where they met, and there he met up with the girl, who had been waiting for him all that time, having almost given up hope. Because it was the last day he could stay with her, Kouta decided to take her to the zoo and spend all day with her. Her fascination with animals she had never had the chance to know of (such as elephants and giraffes) surprised Kouta, and he took delight in her joy from this, as well as an everyday ice treat he bought. They enjoyed themselves all day, and this created a strong bond between them, stronger still for the girl who had never known anything like this before. Both of them were sad because of the little time they had together passed so quickly. What Kouta didn't know was that he was so important to her that the thought of his imminent departure crushed her heart.
When she learned he was going to a nearby festival, she begged to go with him, but he said that he promised to go with his cousin. At nightfall, as they were returning on the bus, the girl, in a trance-like state, arguing with an inner voice, began choking Kouta. When she woke up, she apologized, then startled him again as Lucy asked him, if someday she couldn't stop murdering, to kill her. Kouta was unable to connect this conversation to the recent killings, and soon after forgot about it.
When they had returned, the girl inquired Kouta as to his cousin's gender. Not wishing to hurt her feelings, Kouta lied and said his cousin was a boy. Kouta then went to the Kamakura beach with his cousin, Yuka, and his sister, Kanae, to play. Kanae collected shells to show her brother, but Kouta said they weren't pretty enough, prompting Kanae to kick him, swearing that she would seek better shells.
Upset about his impending return to Hokkaido, Yuka, developing a crush on Kouta, asked Kouta if he wanted to say anything to her before he left. At that age, somewhat ignorant of girls' feelings towards him, Kouta only annoyed her by being unable to answer and was promptly scolded. It was at this point that Kanae returned with shinier shells, finally earning his praise. Later, Kouta realized he hadn't thought to ask the horned girl for her name, leaving it shrouded in mystery not just for him but the audience as well.
Night came, and Kouta and Yuka went to the festival together as they agreed. During the festival Yuka began crying over her inability to cut out shapes at a model carving stall and hugged Kouta, begging him not to leave for Hokkaido. Kouta embraced her as well to console her, unaware that the girl from earlier was watching them. Moments later, people began to panic and ran away, saying that a bomb had gone off. Concerned, Kouta's father panicked and called for the children, finding Kouta and Yuka quickly but becoming worried over Kanae's absence. Kanae appeared soon after, terrified and covered in blood, saying a horned girl had killed people in front of her. Kouta immediately thought of his friend but denounced Kanae's tale as being utterly fictitious. In any event, Kouta's father decided to take the first train back to Hokkaido, concerned that the 'bomber' might still be in the area. Saying goodbye to a tearful Yuka, Kouta promised that he would visit her the next year, just before setting off. In the manga, Yuka and her mother saw the family off; In the anime, only Yuka was there.
On the train home, Kanae kept insisting her story was true and that a horned girl did kill people at the festival despite Kouta brushing it off as a lie, while authorities insisted on the story of a bomb going off. When the girl mentioned above appeared in the train car, Kouta was surprised and happy to see her despite Kanae's alarm. Kanae defensively jumped in front of Kouta, trying to protect him from who she saw as a killer. Kouta angrily denied Kanae's account that his friend could be responsible for so many horrible deaths and finally slapped her, reducing his little sister to tears when he said he hated her. As she pleaded for him not to hate her, the horned girl split Kanae in half with an unseen weapon, and soon after beheaded their father, before telling the horrified Kouta that Yuka would be next. In a mixture of grief and rage, Kouta assaulted her, demanding that she stop killing. Somewhere in his demeanor, she saw something and realized her hideous mistake. The girl ran away, leaving the traumatized Kouta alone and covered in blood, surrounded by the bodies of his sister and father.
What happened to Kouta between this point and his coming to Kamakura again is left up to speculation; Presumably, other family members cared for him in the period between his release from possible mental therapy and the start of the series. He had spoken to the girl about his grandmother in the present tense, but there is nothing more said of her. All that's known for sure is that after the murder of his family, he repressed all memory of that summer trip to preserve his sanity. His new memories consisted of his father instead dying in a car accident and Kanae passing away from an extended illness. The anime briefly speaks of Kouta staying in a hospital for a prolonged period, but for just how long and what type of hospital it was is never explicitly stated.
Returning to and reunions in Kamakura
Eight years later, he returned to Kamakura in the Kanagawa Prefecture to attend college and went to meet his cousin after arranging to stay with her family while at school. To her dismay, he did not seem to recall either those childhood times or her. While walking on the coast beach where they used to play many times in their youth with Kanae), they encountered a young woman, with long pink hair, nude in the surf and completely amnesiac, with a childlike personality and horns on her head. Closer inspection revealed her horns were indeed real (as opposed to costumery), leading Kouta to flash back to a blurry, forgotten memory. Instead of taking her to the police, they decided to take her to Kouta´s new home at Maple House, the former restaurant Yuka's mother owned, where he would live rent-free as part of a maintenance agreement. They decided to name the girl they found "Nyu" after the only word she seemed able to speak.
At night, while Kouta was unpacking, the seashell Kanae got for him fell out of his bag. Yuka recognized the shell from the last day of their summer vacation, the same day his family was killed. Kouta's sad face while looking at the seashell caught Nyu's attention, and thinking the shell is something wicked, Nyu picked it up and promptly cracked it in half, much to the two cousins' shock. Kouta was instantly infuriated and began to shake Nyu, demanding to know why she did that. Nyu, terrified by his reaction, runs away from the house. Yuka goes after her after suggesting why Nyu did what she did, and that Kouta should honor Kanae's memory with something other than grief and bitterness.
After some time, Kouta decided to go after Yuka as well. When leaving, he encountered two police officers, who showed him a picture and asked if he saw the girl in it, whom he recognized as Nyu. When Kouta asks what the girl had done, he is told by the younger police officer that she is a dangerous serial killer, though the second policeman claimed his partner is merely joking, and that the girl was just missing. Nevertheless, Kouta lies to them and goes to find Nyu before they do, not believing someone with her mental state could be a killer. He finds Nyu at the beach in the freezing water, and Yuka arrives shortly after. They realize Nyu fled there to get shells to replace the one she broke. Suddenly, Yuka takes a blow to the head from a soldier searching for Nyu, that leaves her and then Kouta unconscious. In the manga, Kouta attempted to challenge the soldiers. In the anime, Kouta tried to flee with Nyu, as Yuka was not present, but ends up knocked out in both instances.
At the hospital, Kouta's finds his account of soldiers on the beach dismissed by the police, who were, in fact, covering up for the activities of the Special Assault Team. This deception leads Kouta to distrust the police even further. Yuka told him she could not help him with discovering what happened, since she was knocked out very soon in the manga, and was not at the scene at all in the anime. Both expressed their worries about Nyu, otherwise engaged at the time.
After leaving the hospital, the pair is reunited with Nyu, unaware of where she was, or what she did, while away. Kouta makes an attempt to change Nyu's wet clothes without compromising her modesty, but this leads to a comically timed walk-in by an easily upset Yuka, who also presses him on what he recalls of her. Angered by his response, Yuka leaves, with an upset Yuka now in Nyu's clueless care. Returning to Maple House to check on them, Kouta relates to Yuka on the loss of his family, only for an upset Yuka to realize he truly cannot recall those times, as his account of how this happened differs from what she knows. This revelation cements her decision to live with the pair at Maple House.
Life at Maple House
Shortly after that, a young girl came to visit Maple House to return an umbrella dropped by one of the residents on the night the soldiers attacked Nyu on the beach (Yuka in the manga, Nyu in the anime). Named Mayu, her words quickly made Kouta realize that she witnessed the events that the police deny and Yuka cannot recall. When Yuka returned, the two also quickly realized that something was amiss with Mayu, but the girl leaves with her small dog Wanta before they can act then and there.
Unbeknownst to anyone, Nyu was an alternate personality for Lucy, a ruthless killer with an agenda to replace the Human race with beings like herself. She was the childhood friend who murdered his family, and as Lucy, she still remembered Kouta and continued to love and adore him. This love also spares, reluctantly at first, Yuka and the other residents from Lucy's wrath. Switching personas in front of the cousins and their young guest when Nyu is injured, Lucy departed with her personality recalling the events of eight years ago, but her Nyu side and Kouta himself still in the dark. Nyu's activities while away would affect Mayu as well. Injured in the midst of a fight between two Diclonius, Mayu, whose relationship with her family at home was deeply troubled instead had the hospital call Maple House, with Kouta picking her up and paying the bill, which Mayu promised to repay. Taking her back home for food and persuading her to stay for the night, neither Kouta nor Yuka could get Mayu to reveal anything about her home life. Finding that she had left the next morning, they realized (Yuka in the manga and Kouta in the anime) that they should see to Mayu's care and well-being themselves.
After speaking with a local beachfront vendor who had aided Mayu, they confirmed what they had suspected, that the young girl was a homeless runaway. With Nyu returned as mysteriously as she had left, the three prepared to take Mayu in more or less permanently. Once more, events differed between the two versions of the story right after this. In the manga, Mayu found many difficulties that made the hard life she'd gotten used to no longer possible, and reluctantly turned to Maple House as she had no other choice. In the anime, many of these same difficulties came at Mayu, who found herself confronted by policemen concerned for her safety and for her loitering on the beach. In this case, Kouta and Yuka showed up, claiming to be Mayu's family, there to retrieve her after an argument. The end results were the same. When Mayu came to Maple House, she was surprised by an offer to live there on a regular basis, a birthday cake provided by the vendor she'd befriended, and the return of her dog and at one time only friend, Wanta. Within a few weeks, Kouta and Yuka persuaded Mayu to reveal her home address. The two met with Mayu's mother and were privately shocked and concerned when the mother in effect signed over custody of Mayu to them without any discussion. But they agreed to not discuss this out of courtesy to Mayu, and since this enabled her to attend a new school closer to them, it was an outcome they chose not to dispute. In short order, Mayu became a happier girl, with the others more comfortable for her happiness. They would deal with the problems of Nyu's childish if not infantile behavior in another way.
At some point, Kouta and Yuka decided to bring Nyu with them to their college classes, likely after undepicted events made leaving her alone at home unacceptable. Her horns hidden by bows, and her having learned to say one word besides 'Nyu,' the two sought to keep her under watch but also out from scrutiny. This custom became awkward one day when Nyu encountered Lucy's sworn nemesis Bando in what mostly came to be a comical interlude. An encounter of a far more evil kind awaited Kouta on a day that started with Yuka rousing him by way of kicking at him. Departing for a class, they found that their teacher was a Professor Kakuzawa, a man with a reputation equal parts sleazy, harsh and flaky. All this aside, none of them realized that not only was the Professor the son of the villainous Chief Kakuzawa, the prime enemy of the entire series, but also the one who had secretly engineered Lucy's bloody escape from the institute.
After Nyu had spoken up at precisely the wrong moment, Kakuzawa recognized Lucy. The fast-talking practiced liar convinced the cousins that he was Nyu's relation and threatened them with arrest for not reporting Nyu. Kouta and Yuka in effect surrendered custody of Nyu (which they never had legally in any event) and left her with her supposed 'Uncle.' Back home, a tearful Kouta found two more things wrong with the day in question. A sharp if a subtle comment from Mayu told him that an embarrassing incident with Nyu in the onsen was not forgotten, and had placed him in Mayu's sights as a possible menace, just as her sexually abusive stepfather had been. Then, to both his and Yuka's shame, Mayu questioned whether or not the Professor had told them the truth about being Nyu's uncle. Considering what a bad reputation the Professor had, Kouta went off to retrieve Nyu, lightly rebuffing Yuka's offer to join him. What he found back at the lab would have far-reaching implications for the manga series' final third.
A grim thread emerges
Upon reaching the Professor's lab, Kouta met Doctor Arakawa, the Professor's overwrought assistant, who confirmed Mayu's theory that the Professor had been lying since he didn't have a brother (although this was also not entirely accurate either). But instead of finding Nyu, they found the Professor's body, his severed head nearby it, and that his head had small horns on it, though different to Nyu's. Outside their presence and possible knowledge, the Professor's effort to rape Nyu had morphed into an offer of alliance with the awakened Lucy, followed by a murderous rejection that would only be fully explained much later on. For the moment, Kouta accepted Arakawa's admonition to forget all he saw there while finding his paranoia excited by her description of what happened to horned people. As she cleaned up the mess and informed the Professor's family, Kouta left, wondering again what had become of Nyu. Returning to Maple House, he later accepted Yuka's offer to travel with him while he looked for Nyu. For her part, Mayu (who subtly became more comfortable around him again, possibly due to his not menacing her) elected to check the beachfront with Wanta. In both versions, a sudden rainstorm forced Kouta and Yuka to seek shelter, as well as answers concerning each other.
Inside a rest shelter in the manga, and a shrine in the anime, the pair huddled for warmth, and eventually began kissing. Notably, the manga version almost reaches the explicit for how it affects the two would be young lovers. In either version, Kouta says that while he still cannot recall Yuka from their childhood, he remembers feelings about her, including caring for and liking her. This recognition seemed to reassure Yuka to a degree. After some version-dependent embarrassment for Yuka, the two departed and found Nyu nearby in her Lucy persona. When Lucy pretended to be a coherent Nyu and tells them that she must go from their lives, Kouta protested and asked her to stay. Realizing that the truth is the only way to protect Kouta from the danger that follows her, Lucy attempted to give him closure by fully confessing who she is. At the last minute, though, she lost her nerve and reverted to Nyu, who they finally took home again, to a happier if still not a peaceful Maple House.
Once back home, Nyu resumed a pattern of intrusiveness that upset Kouta's peace of mind and his relationship with Yuka, though it may have saved his relationship with Mayu. Waking up in his futon, Kouta found himself roused by Yuka, who pulled away his covers to find a nude Nyu cuddled up to him, something Kouta himself hadn't realized. Unfortunately for an enraged Yuka, Nyu became curious about her breasts and began mercilessly groping Yuka, leaving her overwrought by the sensations, and Kouta fixated on the alluring sight. Adding to the embarrassment, Mayu walked in on the scene, deciding that all adults are perverted. But curious Nyu briefly groped Mayu's young body, only to leave disappointed and to leave Mayu upset, for the grope, and for the unstated opinion. While never stated in-story, this point seemed to be when Mayu stopped regarding Kouta as a possible direct menace, perhaps out of some recognition of Nyu's antics.
Yuka's irritation always appeared to travel in Kouta's direction, even in an incident like this, and so he was warned to be on his best behavior when a high school friend of hers came for a visit. She also directed him to fetch groceries and cleaning supplies. While complying, Kouta encountered a young woman whose skirt was caught by a gust of wind, revealing to her shame that she wore an adult diaper. Coming back home, later on, Kouta was mortified to find that the young woman he had encountered was, in fact, Nozomi, the friend Yuka had been expecting. Her nerves on edge, Nozomi was forced to flee as her bladder gave out again, exceeding the capacity of her current diaper without a ready replacement. Outside, Kouta and the others searched for her, with Kouta again finding her as she removed her diaper, though soiling her blouse in the process, leading everyone to know her secret. Thinking fast, Kouta knocked Nozomi into a puddle, obscuring her shame with a less embarrassing stain. Out of gratitude, Nozomi took the Yuka-blow meant to punish Kouta for pushing her in. Nozomi apologized for her cowardice, but Kouta admonished her not to think of herself in such a way. With his and Yuka's encouragement, Nozomi soon enchanted the entire household with her operatic voice. Nozomi developed a pronounced crush on Kouta as a result of his kindness, one of which Kouta seemed to remain unaware.
Kouta began to become concerned about the overdue return of Mayu and Wanta, out for a walk, but this was alleviated when Mayu returned with a new companion, a girl named Nana. To the household's shock, the young lady had horns just like Nyu, and Kouta began to pepper her with questions, hoping to solve the mystery (in his present-day memory) of where Nyu originated. But in fact, Nana was from the same facility as Lucy/Nyu and had been horrifically wounded by Lucy, and the mere sight of Nyu was enough to cause Nana to attack her, injuring Nyu and wrecking the house in her path. The view of the Maple House residents, especially Kouta, instantly taking Nyu's side put Nana in tears and flight, with Mayu pursuing her.
While the attack upon Nyu was enough to awaken Lucy, she was feverish and exhausted, only able to be cared for by Kouta, and remembering troubling aspects of her life. Upon reflection, Lucy decided that Kouta could not be safe or happy when she was around, and so used her will to induce her personality to recede entirely for Nyu. Nyu, for her part, took Kouta's words about his regrets with Kanae and acted to aid him in a way only she could, or only she would ever likely think.
When Kouta again found her, Nyu had cut her hair and was wearing clothes too small for her. She had done this in a sweet if an awkward effort to impersonate Kanae so that Kouta's deceased little sister could provide him with forgiveness for their last harsh words. A Kouta struck by the tender gesture (perhaps reinforced somewhere in his mind by who was doing this) gave Nyu a hug, one sadly witnessed by Yuka, whose doubts drove her crying to the beachfront, determined to never again go home to Maple House, and possibly even suicidal. In the midst of her despair, Kouta came and got her back, even going so far as to slap her across the face for worrying him so badly. As with Mayu, this incident had the unspoken effect of resolving Yuka's worries about Kouta, and for the remainder of the series, her scolding and hitting of Kouta all but vanished. Kouta would have another young lady to square matters with as soon as a few hours from then.
At Mayu's behest, Nana had returned to Maple House and apologized for attacking Nyu (who she realized did not have Lucy's presence, a sense that Diclonius have to detect one another). However, she refused to come inside, still feeling she was the wronged party, and feeling she still needed to keep watch over Lucy's return. Perhaps made too much like each other, Nana and Kouta clashed until Mayu made staying in Maple House a challenge she pretended that she felt Nana could not handle. Kouta later joined this with some reverse psychology of his own, slowly leading up to the idea that Nana would have to contribute to the house with chores to pay her way. Within a day of enjoying simple creature comforts not available as a test subject, Nana was comfortable in Maple House and even happy. When she left suddenly to deal with the threat of another Diclonius, the clash was entirely forgotten, or at least put aside, by Kouta, who left to retrieve her from the beachfront, his worry over young girls like Kanae overriding any other problems. What happened next defines a climactic point in the manga and the conclusion of the anime.
End Of The Anime
In the anime, when Kouta and Nyu arrived at the bridge to Enoshima Island, they found a barricade of police at minimum knocked out on the ground, possibly dead, in a scene that causes continuity problems. That aside, Kouta proceeded ahead of Nyu and found Nana, stripped and tormented by Mariko, who asked the permission of her handlers to kill him. The concern that Kouta and Nana showed for each other intrigued Mariko's overseer Shirakawa, who approached them. Unknown to Kouta, Nana protected him (and anyone else she targeted) by disabling Mariko's vectors, causing her and her control force to withdraw eventually. After Nana had fallen off the bridge (where her 'Papa' Kurama recovered her), Nyu made her way over, which panicked all of Mariko's group except for Mariko herself, since she could sense that Nyu was not Lucy, at least in the respects that mattered. While Shirakawa urged caution, Isobe acted precipitously and had the present soldiers fire on Nyu, which awakened Lucy. Kouta, only seeing Nyu, ignored Shirakawa's warnings about Lucy, until an annoyed Lucy split Shirakawa in two, killing her and shocking Kouta's dormant memories awake. Realizing that his friend is also the killer who murdered his family, Kouta grudgingly accepts Lucy's request that they meet later on when she has settled matters with her enemies. Her humming of the song Lilium doubly confirms how they once knew each other.
Unknown to Kouta, at that same time, Yuka and Mayu discussed him back at Maple House. The observant Mayu tells a nearly despondent Yuka that Kouta seems to favor helping girls without anywhere else to go. In turn, Yuka related at least part of the story of how Kouta lost his family, which surprised Mayu. Mayu also complimented both Kouta and Yuka, calling them the Papa and Mama of Maple House, a compliment her manga counterpart could not quite bring herself to say. Confident that everyone now missing would soon return, Mayu also observed that Yuka was in love with Kouta, something Yuka conceded.
After Lucy had settled matters with people as varied as Bando, Mariko, Nana, and Isobe, she met Kouta by the stone steps of Jouju-in Temple, there to talk out what they could in the time Lucy had before the series' real antagonist would send his forces against her. Lucy attempted to explain her purpose in life, and how only the thought of her love for Kouta kept her from fulfilling it. Stating she must leave, Kouta attempted to stop her, confessing his love for the little girl she once was, and for Nyu. Notably, despite accounts to the contrary, Kouta does not forgive her crimes in this version, stating outright that he can never do this. His tone is simply more sympathetic in the anime version. While their talk ends with a kiss, it is one laced with regret at what could have been.
Kouta is next seen in a brief epilog set some months later, with him recognizing that Yuka keeps setting a place at mealtime for Nyu. She admits to missing Nyu as well, and both Mayu and Nana, who is now living there, both seem at peace and glad to be there. With mealtime done, Kouta's music box stops playing, Wanta starts barking, and the Grandfather Clock that so fascinated Nyu begins working again, all very suddenly. At the front gate, Kouta sees the image and silhouette of a visitor, but the viewer never learns whether, as strongly suspected, it is Lucy/Nyu, returned to them.
As of 2017, no new anime series has emerged to resolve the loose threads in this.
Mariko in the manga
In the manga, Kouta has almost no role in the events surrounding the confrontation between Mariko, Nana, and Lucy. In this iteration, the police barrier is up and running, though Nyu manages to slip past it. Kouta remains to wait for the others to return.
When they do, Nyu is perhaps more subdued than usual, though Kouta doesn't indicate whether or not he even notices that Nyu has lost her horns. Nana, wearing only a coat, rides on Kouta's back. Nana shows her gratitude that, contrary to his normal behavior, he asks no questions of them. Kouta is among those who observe Nana burst into tears at the thought of Mariko's loss and short life.
Events escalate in the manga
Six months after this, Nana's narration informs readers of changes to Maple House. Nyu has matured, with no sign of Lucy in all that time. Nana herself has moved in, and Nozomi spends more and more time at the Inn while pursuing her studies. Mayu is still awkward around guys, though presumably a bit less so around Kouta. Nana observes that she has found peace with both Kouta and Yuka, the latter of whom she has realized is in love with Kouta. As for Kouta himself, Nana relates that he does his best to be a protector of their home and its residents. Also at some point, Nana has learned about Kouta's suppressed childhood memories, though whether this is something told to her or observation is never made clear. Also unclear is whether or not any of the other ladies besides Yuka are also aware of this. It is possible that Yuka told the others to explain away awkward moments with Kouta, or that they too observed this for themselves, but again, nothing is apparent either way.
Despite Nyu's maturity, Kouta and Yuka still take her with them to college, presumably to fewer antics. Remembering the late unmourned Professor Kakuzawa, Kouta also worries about running into Dr. Arakawa; a fear realized almost as he thinks it. Arakawa, who has problems of her own, takes Nyu 'hostage', or at least refuses to let her get away. Kouta can think quickly and teases Arakawa with a vulgar poem about her figure (one Yuka notably does not call him out on), and then shakes her entirely by pointing out the remnants of Nyu's horns. To Kouta, he is merely using the fear Arakawa expressed about all horned people to his advantage. Arakawa, however, blindly panics when she realizes her captive is Lucy herself (or at least is so to her fevered mind). During this panic, the trio makes good their escape, and Nyu is no longer able to go to school with them. Sadly unknown to Kouta, while this is happening, a sadistic intruder is menacing and attacking Mayu, Nana, and even Wanta back at Maple House. The one who stopped the attacker, the mercenary Bando, is waiting when the trio return, immediately recognizing Nyu as his sworn enemy Lucy. Brushed aside by Bando, Kouta sees the blood and carnage inside their home and begins to feel helpless against the chaos just outside his knowledge, and indeed his control. In a brief agonized moment, Bando's words about pursuing a horned killer even awaken memories of Kanae. This time, the calming words of Lucy (who he still thinks is Nyu) are no comfort, and Kouta decides to seek out whatever advice he can from Doctor Arakawa.
Arakawa speaks no comfort to him, only foretelling doom if he keeps Nyu around. Worse still, the doctor follows Kouta back home, giving her and therefore the forces serving Chief Kakuzawa the location of Lucy, their prime target. Unable to know this, Kouta instead follows Wanta to the rest shelter seen many times throughout the series, finding Nyu, Mayu, and Nana. There, he chastised all of them for making him worry, a declaration that has Nana crying and the group all headed for home. While the dinner that follows is peaceful and even joyous, the seeds that Kouta has sewn come back at the residents. While awaiting test results for Nozomi, armed intruders burst in, demanding the surrender of Lucy and being none too gentle in enforcement.
Enraged by the treatment of his housemates, actually his second family, Kouta twice grabbed at Nousou, the apparent leader of the force. The first time, he was gun-butted away and warned of being shot by the Agent, till the man-handling of his loved ones compelled him to grab a gun and hold it directly to Nousou's head. The arrogant scientist belittled Kouta's courage and resolve, calling him unable actually to kill him. Kouta conceded that much but then shifted his threat to Nousou's jaw, a wound survivable but searingly painful. To keep true to her threat (and possibly needing Nousou alive and talking for other reasons), the Agent shot Kouta, whose wounding shook the quaking Nyu out of her stupor. While Kouta fell unconscious, Nyu gained the same power as Lucy for the first time, along with larger horns and a level of ability never seen by either. Fading in and out as he went, Kouta witnessed the death by bisection of the Mariko clone named Cynthia, which triggered the return of his childhood memories, especially those regarding Kanae's murder. Though it is unclear whether Nyu, Lucy or some mix of the two personas entirely turned back the invaders, the effect on their face was evident when Kouta proclaimed he now knew how to avenge his Papa and Kanae, and who was responsible for their deaths. Kouta again became unconscious, and a despairing Lucy/Nyu left Maple House for the last time.
Under unknown circumstances, authorities summoned medical help for those at Maple House, and they pressed no charges against anyone living there. Whatever the case, Kouta remained insensate to events around him and certainly outside his circle. While he was in the hospital, Mayu, his surrogate daughter, watched over him while Yuka and her mother (Kouta's Aunt) argued over the fate of Nana. Yuka indicated that he was talking in his sleep, perhaps having nightmares, and this seemed to be related to his awakened memories. Even though Kouta never showed any extra sensory perception (putting aside the debate over how Kanae saw Lucy's vectors at the carnival), he seemed to stir from his near-comatose state as Lucy left the sinking Diclonius Research Institute. Acting like he sensed Lucy's return to the mainland, Kouta made for Yuigahama Beach, despite his still very severe wounds, and met her as her pod came ashore.
To Lucy, the state of Kouta's mind was clear. He did not wish her to touch him, and he made it evident very quickly that he could never forgive his family's murder. Despite this clear line, Kouta offered to hear her out as Lucy tried to explain her actions. Despite not wishing to be held by her, Kouta relented and allowed her to carry him up the stairs of the Enoshima Sea Candle, a view he pointedly reminded her Kanae had wished to see and now never would. Lucy's pleas for him to return to the hospital fell on deaf ears as she prepared to give her version of events. Without explicitly mentioning his lie about Yuka's gender when they were children, Lucy tells him how she thought Kouta betrayed her, and that the murder of his family was punishment and isolation for him so that she would have him all to herself. Lucy also explains about the (at minimum) three personalities inside her body; Lucy herself, Nyu, who he mainly knew of, and the voice of her DNA, the principal thing urging her to kill all humans. She explains Nyu as being Lucy's vision of her ideal self; peaceful, loving and able to live with Kouta and the others. She finally offered up the thing she had escaped for, and indeed lived for, since that terrible day aboard the train: To apologize to Kouta. Kouta, however, will hear none of it, his mind made up.
In his rejection of her explanations, he also tells her why they are unacceptable. At the end of this counter-argument, he makes a simple offer: Though he can never forgive and even hates her, Lucy is part of Nyu, who he would miss if she were gone. If she stops killing, she may remain living at Maple House. Lucy agrees, seeing surprising tenderness in his demeanor, yet she also makes him let her call the hospital. Once more, events outside Kouta's view make things difficult.
Confronted by a gun-wielding Kurama, Lucy recalls her promise to Kouta, preparing to live and die by it. To her shock as much as anyone else's, the DNA Voice personality takes her over entirely, severing Kurama's arm. Kouta is witness to none of her struggle, only arriving to see the spilled blood she had sworn to avoid. In no uncertain terms, Kouta rejects her forever, stating his hatred, his contempt, and his fervent desire never to see Lucy again.
Unknown to him, a struggle takes place inside Lucy's mind, this while Kurama ignores the pain of his severed arm and prepares to shoot her once more. Kouta instead takes the bullet, which, coupled with his prior wounds, almost certainly means that he will die. When pressed by Lucy as to why he would do this for someone he hates, Kouta attempts to hide his true feelings behind the excuse that, since Kanae had died with their business unfinished, he didn't want the same thing to happen with Lucy. But in his muddled motives, Kouta drove both Lucy and Yuka into despair. Lucy loses control and destroys the Sea Candle's tower, which Yuka, who knew Kouta was atop it, witnesses.
It turns out that Nana rescued Kurama from the ruined tower, but she like the others is left wondering about Kouta's well-being. Around the telekinetic storm that Lucy has raised, the world waited in terror. Neither the JSDF High Command or the First Escort Naval Fleet, equipped with specialized technology meant to combat Diclonius have any clue as to how to handle Lucy's threat. As she held the dying Kouta, Lucy's pain and rage only amplified as he body began to dissolve from overusing her power. Her pain also cleared her head somewhat, as she realized her power could also heal Kouta, though the effort would likely hasten her death. Overcoming the objections of the DNA Voice for all time, Lucy undertook to heal Kouta, singing the song Elfenlied taught to her (or more precisely, Nyu) by Nozomi. As she anticipated, the strain of the precision of healing Kouta, combined with turning back military attackers, continued to eat at her body's integrity. When Kouta came to (recovered from dying but still in need of a hospital's care), he found Lucy had melted into a pile of flesh, bone, and muscle, still alive and in agony. As the other ladies from Maple House arrive, Nana confirms her condition is and her regrets, including not (as Lucy) spending more time with all of the residents, are plainly stated. Most of all, she wanted Kouta to know her sacrifice was well worth it, if only he were alive and one day happy. A group of armed soldiers, led by a fanatical intelligence operative, stormed the damaged tower, threatening them all, and demanding Lucy's now pointless surrender.
Nana considers attacking the soldiers, but Mayu objects, based both on not wanting Nana to become a killer, but also, in stark contrast to early suspicions, faith in how Kouta will handle this. The Operative threatens Kouta with being shot for treason. Not wishing to cause harm to the people she cared for, the essences of Lucy and Nyu (shown as separate spirits) departed their shattered body. Nana, however, senses that one remains inside the dying form, the Diclonius DNA Voice itself. As Nana pulled Kouta away, the Voice used her vectors to kill the Operative and all his soldiers. Their spirits departed, Lucy and Nyu tell Kouta that the rampage the Voice will undertake could destroy the world and that it is his responsibility, as per their childhood promise, to stop the Voice by killing their body. Moreover, they tell him that, even if she could recover, her life will bring only death. As the spirits fade, Kouta prepares to kill the body, since the spirits can no longer restrain the Voice. Out of the love he denied in a hateful moment, Kouta could not bring himself to kill the body, until the Voice, in agony and reluctantly impressed by the truth of his love, itself asks him to kill her. Kouta then killed the girl he had known as Nyu. As the series concluded, Kouta is shown leaving the hospital after a stay still required by his repeated wounding. The period appeared to be as much as four months. The ladies of Maple House make an effort to repair the damage to the residence before he returns home. To the audience, Kouta relates how the war that the series' real antagonist, Chief Kakuzawa, wanted came to pass, threatening Humanity with extinction, both from Diclonius attacks and a general birth ban put in place as a countermeasure. Kouta seemed confident of humankind's survival. Kouta and Yuka became closer as she urged him to stop leaving her so often.
In an epilog set ten years after these events, there are again many unknowns in Kouta's life. The fate of any other major character is unrevealed, though it seems he is still living in the Kamakura area since he is shown to have visited the site of where he and Lucy first met every year. This annual journey was the result of a new promise the dying Lucy/Nyu made to him, that one day she would be there to meet him. With him on this tenth such visit is his daughter, called Nyuu after his fallen friend. While Little Nyuu's mother is not named, the girl is the spitting image of the child Yuka and indicates how her mother would be angry if they were late in getting home. Kouta revealed some few details of his reasons for coming to that place and was prepared to give up when his daughter found a bottle, buried in the ground near where child Lucy buried her puppy. Inside the bottle are a precious keepsake and a message from the young Lucy. The message is a confession of love to Kouta, including the desire to marry him. This knowledge relieves and overjoys Kouta, who had, with all Lucy had done, wondered if her friendship was real or faked because of her agenda to change the world. The letter also revealed her actual name, Kaede. Little Nyuu, who earlier had told her father about befriending twin girls who lived in the area, now spotted out those twins, one of whom she called Kaede. Together, the twins state that they have been waiting for a special friend. That friend seemed to be Kouta himself, with the implication that these girls are the redeemed and reincarnated Lucy and Nyu. The very last image in the series is Kouta crying tears of joy.
- It is only through Kouta's narration at the end of the manga that we learn of the war that followed Lucy's death.
- Kouta's name is romanized as Kohta, most notably in ADV's promotional materials.
- Kouta appears by himself on only four manga chapter covers, a surprising number for the series' secondary lead. However, male characters appear only a total of five times on these covers, excluding the cover cast shot of the final chapter.
- Besides the college where he was accepted, Kouta applied for fifteen other universities.
- In his latest interview in a magazine published in August 2016, Lynn Okamoto says that although Kouta was a major male character, Kouta's roles in the story were too much passive and looked like a mere onlooker. He stated that Ryouta in Brynhildr, for example, played a much more proactive role protecting the witches and other people.