I have contracted a strange disease called ``If I don't have sex once a day, I'll die''. She is a virgin and has no girlfriend, let alone a girlfriend, and is on the verge of despair... However, her childhood friend Akari, who lives next door, comes over worried. ``It'll be a problem if I disappear...I guess you don't have anyone else.It's okay because it can't be helped,'' they said as they both had sex for the first time. Akari, who was doing it out of a sense of duty, enjoys playing with each other in daily sex.