Prosperity or Death (繁栄か死か / はんえいかしか / han'ei ka shi ka ) is the twenty-second chapter of the Elfen Lied manga series.
Professor Kakuzawa tells Bando that his battle with Lucy has left him infected with the Diclonius virus and that any children he has will be Diclonius, who present a threat to all humans. Her vectors carry the virus and spread them when she attacked Bando. When Kakuzawa implies that this is somehow a happy occasion, an enraged Bando attacks him but is contemptuously batted back due to his injuries. Chastised but not bowed, Bando protests that the same result will occur if he simply never has kids, but Kakuzawa insists that his castration will provide scientific insight into the Diclonius threat. However, there seems to be a way Bando can avoid this loss.
Back at the Maple House, Kouta, Yuka, and Nyu return and Mayu has already drawn the bath and made dinner, insisting that this is repayment for having a place to live. Kouta visits the onsen first, and Nyu, naked, climbs in with him and shoves his hand against her breast and rubs against him, getting on top of him in an embrace just short of sex. With her rubbing up against him, Kouta cannot think straight, also fearing that Yuka will walk in and see this spectacle. Instead, it is Mayu who walks in, and immediately she becomes fearful that Kouta may secretly be like her abusive stepfather. In any event, she quietly despairs that all men are the same as she leaves.
Kakuzawa speaks of an antidote to the virus that is in development but is not ready as yet. He offers Bando a kind of trade in exchange for letting him dodge the operation. Kakuzawa shocks Bando by offering to fake his castration in medical records if Bando agrees to sire Diclonius children.
- This chapter establishes Mayu's doubts about Kouta, a theme which will persist for much of the series.
- Given the chapter's plot, it seems possible that the original title was closer to "Posterity or Death."
- The chapter cover features Yuka in a spring/fall hoodie, sporting a black shirt/blouse.