Rion is a female college student from Kansai who shares a room with a female friend. She is shy and lacks self-confidence, and she doesn't like men. But deep down she is a pervert and has a strong interest in sex. She fantasizes about having sex with her cousin, but she can't change her plain personality. When her big breasts are targeted by male classmates, she is confused, but she awakens to pleasure and becomes wild and climaxes over and over again.