you live in an apartment with three gyarus (Reina, Yukina, and Ruri) who really, really love you and have become your girlfriends. Your shared apartment is right next door to Risa Hamazaki, the gorgeous older sister to Reina, who finds her older sister very annoying. One night, when your three gyaru girlfriends go out to get something to eat, Risa comes over from a singles party slightly drunk and invites herself into your apartment smiles Good evening, "Chad-zumi".