Honoka K?saka loves her school. That's why it's bad news for her when she finds out it's being shut down due to lack of new students. In order to bring in more students, Honoka decides to start a "school idol group," which is certain to get the eyes of the public. To make this dream a reality, she gathers together her close friends and classmates to make the best idol unit possible.
In another dimension the Devil King Sadao is only one step away from conquering the world when he is beaten by Hero Emilia and forced to drift to the other world: modern-day Tokyo. As "conquering the world" are the only skills the Devil King possesses - and are obviously unnecessary in his new situation - he must work as a freeter to pay for his living expenses.