Tsutsujimori Shou

The senpai of Marina at the office. He is a low self-esteem virgin student who works there because his uncle, Marina's boss, gave him the job. By some coincidence, he is also neighbors with Marina.

He is always depressed because the girl he has a crush on is in love with some other guy. Marina encourages him to confess to his crush before it is too late.

When he finally confesses, it ends up being too late. Marina and Kenji (who is only her friend at the time) feel bad for him, so Marina takes him out to drink and, after a few drinks, they have sex. From there they start their strange relationship of being more than friends but less than lovers, where Marina tries to give him tips.

Spoiler

He gains more confidence after having sex with Marina and starts spending less time with her. He finally find a new girl that he likes and breaks up with Marina. Some time later, he tries to get her back but she refuses because she found someone to love too.