It’s summer vacation and your parents are heading overseas for work, leaving you with your 5 little sisters: typical lovestruck imouto Aya, modern tsundere Rio, timid and shy Hiyori, lively and perverted Koharu, and the bookworm Michika who's a lovable Sadist. With no distractions and ecchi happenings one after the other, how far will you go with them?