This unnamed girl is the girl Michiru met when she was about to commit suicide but ended up preventing both of their suicides. They became best friends, spending some time together, going out to fast food restaurants, karaokes, arcades etc.
During the visual novel there are rumors about how she was dating a decades older man with wife and children, treating her like his misstress. there were photos on the internet of she and the man making her having sex with other men. One time Michiru saw a pregnancy test fall from her bag but she decided to say nothing.
Soon after Michiru finds out a photo of she naked on her desk who tore it off and shoved the photo into the paper. Soon she confirms to Michiru this rumors saying that she loved him, doing all the things he told her to do. she even had an abortion without telling anyone after getting pregnant. She show in front of Michiru with her clothes tattered and torn, her face full of bruises and her hair hacked with a knife, Apparently she was rejected by the man and decided to finally kill herself, saying goodbye to Michiru she jumps from the roof, this provokes a heart attack to Michiru for the shock of watching her best friend dying.
Main article: Relationships of Girl