Marina at the time where she met Kenji Azuma with whom she is good friend. She is the Kouhai of Shou at the office. A new office lady in her first year at work. She works as an office clerk at a small construction company. When she was a student, she dated an older man, so she has had some experience with men. Although it has been a while since they broke up, the pain from the breakup has not yet fully healed. Although she doesn't show it on the surface, she feels lonely. As she dates Tsutsujimori, she becomes aware of her own sadistic side. With Tsutsujimori, who was still a virgin, she uses the techniques she learned from her sexual experiences with her ex-boyfriend. [Translated from Gyutto] Since Shou is always depressed because the girl he has a crush on, is in love with some other guy. Marina eggs him to confess to her before it's too late. But it's too late. Marina and Kenji (who's only her friend at that time) feel bad for him, so she takes him out to drink and, after a few drinks, they fucks togethers. It's how start their strange relationship, more than friends but less than lovers, where Marina tries to learn to him some tips. He takes more confidence after having sex with Marina and starts spending less time with her. He finally find a nw girl to like and breakup with Marina. Some times later, he tries to take her back but she refuses because she too find someone to love. Even if their relationship was only physical, Marina feel bad when Shou dumped her, thinking that never someone would like her. Afterwards Kenji comforts her. They spend more time together as friends, talking, having dinner... And her feelings for him starts to growing, little by little. A few month later, after one of their date, Shou comes back to Marina's apartment to take her back but Kenji argued with him and confess to Marina and she said yes. Shou leaves and Marina and Kenji start their new relationship. Even if Marina fell for him, she lied to him that she didn't fuck with Shou, because that would sadden Kenji very much.