Aspiring to become an idol, Ino Sakura moves to Tokyo to live in Mouse House, a dormitory of Rat Productions. Informed of Mouse House's crisis, Ino is told to form an idol group with three "dropout" talents who also live there.
The girls at Mouse House are fired up for a new school semester. After their first day, Hoho tasks them to write a new song for their CD debut and the girls get closer during the process.