エスカレーション～狂愛のフーガ～

Rie is a shy and innocent girl who has just transferred to Saint Yale Academy. After the shock of lost love, she leaves her parents and tries to live out her transfer school life in the dorm. However, when going to class one day she happens to witness a lesbian scene with her upperclasswomen Naomi and Midori. With the academy as the backdrop, a sadistic corruption of pure love unfolds!

[From DLSite]