Ayano Koshima
About
Ayano is Sakuta's classmate. She and Sakuta seem to always end up in perverted situations, mostly regarding her large breast.
She and Sakuta begin dating. Her personally starts to change from shy and timid to an aggressive one as she begins to become overly obsessive about Sakuta. This leads to her trying to cut off Shiori from Sakuta, and ultimately trying to kill Shiori.