以成为偶像为目标的女高中生东优羽，她在学校为自己定了四项规则——“不要使用社群网站”、“不交男朋友”、“在学校保持低调”、“和来自东西南北的美少女成为朋友”，并和她们组成4人偶像团体。
Only a day after returning from the past, Batman and his allies discover that the world isn't quite the same as they left it. The entire island of Japan no longer exists and neither do the heroes of the Justice League. But before they can get a handle on what is going on, yakuza literally start raining from the skies.
