Kaguya Rin is a 26-year-old office worker who has never had a boyfriend, let alone any sexual experience. She takes good care of herself and always puts her best effort into dates, yet somehow her relationships never last long. After being dumped once again, she is feeling down when she is assigned to train a new employee, Tachibana Yamato. Yamato is perfect in both looks and physique, and his honest, sweet personality helps heal Rin's wounded heart. But Yamato is hiding a secret—he is actually Rin's neighbor, and he harbors an intense, obsessive love for her that goes far beyond ordinary affection. One night, Yamato confronts Rin with the fact that he knows about her private habits, and he boldly declares that she belongs to him now. His relentless, possessive love and skilled caresses slowly draw the inexperienced Rin into a world of pleasure she has never known. As their relationship deepens, Rin finds herself unable to resist Yamato's overwhelming passion, even as she struggles with the intensity of his obsession. Their office romance becomes a passionate, steamy affair that neither of them can escape.