[The troubled face of the weak-willed Marin Mita is so Ke'ai it's precious...] Marin is a timid and timid girl. Although she is not aware of it, her appearance and mannerisms strike a chord with men, making her popular. She is given a tutor. His sister's boyfriend, Atsushi. He has a problem. Even though they have been dating for quite some time, Marin's sister is a strict person and won't let him have sex with her at all. Compared to her strong-willed sister, Marin seems weak and easy to get. Atsushi, whose desire was about to explode, made a move on his sister without thinking. However, Marin... accepted. When Atsushi found out that she was weak-willed, his desire escalated more and more...