Several years ago, local heroines—superhero characters who represent towns and perform stage shows in order to raise their town's acclaim—had a boom in popularity. The most famous of these local heroines, Kamidaio, is scheduled to perform in the small town of Hinano, much to the excitement of Mikan Kise's little sister Yuzu. Unfortunately, when Mikan takes Yuzu to the show, she finds out that it has been canceled. She promises her distraught sister that she'll make sure she can see the show. Desperate not to let her down, Mikan asks her classmate, the local heroine fanatic An Akagi, for help.