因为童年时期的某件事而对女性产生心理阴影，为无法性生活而烦恼的大学生2年级学生伊藤努，在大学的社团里认识了新生小山内扬羽。身材娇小、天真烂漫的扬羽实际上是比她年长25岁的新生，和努力梦想中出现的女性长得一模一样。两人因为意外的事情开始了同居生活。

2nd year university student, Ito Tsutomu is impotent due to an accident when he was a young child. He meets first year student Osanai Ageha at a university club. Ageha looks just like the girl that has appeared in Tsutomu's dream. Meanwhile, Ageha looks like a young woman, but she is actually 25-years-old. The two people then begin to live together.