S1 slim beauty stars in a luxurious co-starring emotional drama! The protagonist's girlfriend shares an apartment with two friends, and he occasionally visits their place. He falls for his older, cool roommate 'Tsukasa' and confesses his feelings. She tells him, "If you abstain from sex for one month, I'll do something nice for you," so he begins a life of celibacy—but ultimately gives in and sleeps with her. While she's away, the other friend, 'Sayaka', catches them and ends up confessing to him instead. Circumstances spiral out of control, leading to a twisted, non-stop threesome NTR affair during the girlfriend's three-day absence.