Ino Sakura has just moved to Tokyo to join the newly formed Fruit Tart, an idol group composed of three members besides herself—Roko Sekino, a washed-up child actor; Hayu Nukui, a failed musician; and Nina Maehara, a model who is still waiting for her first gig. They soon begin their new life together in their dormitory, the Mouse House. But there is no time to get settled as the girls awaken to a shocking reality: Fruit Tart is in a deep debt of one hundred million yen and has not even started yet! With the possibility of Fruit Tart breaking up and the Mouse House being torn down if they cannot repay the money, the girls must work their way up from the bottom of idol society by making a name for themselves and writing their own songs. Luckily, Hemo Midori, an experienced idol, is a huge fan of Sakura and decides to join the group. With smiles on their faces, Sakura and the other girls work hard to become popular idols while making sure that each day is as fun as the last. Fourth dormitory of the Rat Production (commonly known as Nezumi-sou)—the place where dropout idol girls live: the former child actor Sekino Roko, musician Nukui Hayu, and model Maehara Nina. Sakura Ino, who always dreamed of becoming an idol, moves in. At the same time, the decision is made to demolish the dormitory. Due to the project launched by the manager Kajino Hoho, Ochikobore Fruit Tart, occupants of the dormitory form a new idol group called Fruit Tart and start their activities in order to repay a one hundred million yen debt.