I'm a virgin with no girlfriend or female friends, when I suddenly contract a strange illness that kills me if I don't have sex once a day. Crushed by despair, my childhood friend Akari, who lives next door, comes to check on me. She says, "It'd be troublesome if you died... and you don't have anyone else, right? Fine, I'll do it." She offers to have sex with me for the first time. What began as a duty-driven arrangement gradually turns into mutual enjoyment through daily sex. But then, Akari's boyfriend suddenly shows up...