僕と里衣菜先輩の秘密の部活動～ミステリアスな先輩が発情してHに夢中になる話～

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... (Source: Irodori Comics)