The Kobayashi twins, Megumu and Mitsuru, were named after historical figures, but only Megumu has grown up with a taste for history. So when Mitsuru is in danger of losing his weekends to extra history classes, he convinces his sister to swap clothes with him and ace his tests! After all, how hard can it be for them to play each other?

But cross-dressing is the least of their worries! Mitsuru is now on the hit list of a popular school bully, and no one but Megumu's weird friends and the girl of his dreams are willing to stand up with him against the attacks. Megumu has fallen in love too, but it turns out her new flame is allergic to girls! Can the twins avert tragedy, or was switching places the beginning of a disaster?!