Sakamoto is a fresh recruit employed at a company where first year employees must live in the company dormitory. His roommate is Shimasa, a guy with good looks who everyone has high expectations of. However, it would seem Shimasa also has a dark side to him. One day, he finds out that Sakamoto has a very sensitive body... and uses that to blackmail him into a sexual relationship. Three Knocks is the Sign For Sex---- Shimasa sexually trains Sakamoto three times... and Sakamoto eventually becomes unable to resist----! * Contains expressions of sexual training, fellatio, creampie, and consecutive climaxes.