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?

Aoi has started college in Sendai, the place where Megumu's parents met and got engaged. And while he and Megumu don't relish a long-distance relationship, they are looking forward to spending time together in such a meaningful place. But romance isn't the only thing to be found in Sendai--the mother who abandoned Aoi and his sister is living there too!