Bakuhatsu Sunzen!! Tenshi no Countdown  

Countdown to Delight, Kitty Pleasure Pack #2 (1), 폭발직전, 爆発寸前!! 天使のカウントダウン, Baku Hatsu

Motoki is a junior high school student who struggles to focus on homework due to his sisters' loud lesbian sexual activities happening in other rooms. He believes that life cannot get any worse until he receives a tutor and falls deeply in love with her, which ultimately leads him to become a sex slave for her.