Hakudaku Shimai ~Namaiki na Ano Ko no Kao ni Bukkakero!~ by Nurejiru - Adult Sex Game

Younger sister Aya and her older sister Mai are both in love with the guys next door, their friends; older brother Yuuto and younger brother Haruto. However, coming home one day Aya is attacked and raped by strangers. Scared and uncertain she won't go to the authorities for help. She can't even bring herself to talk to her sister Mai or friends. To keep anyone from worrying she pretends everything is alright and tries to keep on smiling. Without facing consequences her attackers abuse her again and the number of rapists grow.

Unknown to Aya she was targeted because of jealousy and anger but which of her classmates or friends would betray her? Who would do such a thing? Furthermore, men who rape one girl will gladly rape another.