由森 美咲

Main heroine of the story. Close friend of the protagonist. Together with Yuuji, attending the same seminar.

Alongwith Tatsuhiko and Yuuji has been a trio of friends for a long time. Liked both of them as much but after getting confessed by Yuuji, started going out with him. However because of how busy Yuuji became, started to grow lonely.

And thus, thinking about Tatsuhiko who is repressing his feelings, offered her virginity to him. Trapped by feelings of guilt, started having immoral sex with Tatsuhiko.