After School With Riina Senpai ~How My Mysterious Senpai Got Her Insatiable Appetite for Sex~

Riina's a serious member of the Literature Club, but it seems she's the only one who actually cares... until she meets a like-minded underclassman who confesses to her. She becomes head over heels, one thing leads to another, and after her switch is flipped, her horniness becomes insatiable... (Sour