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----!