A samurai's path leads him to a young waitress whose hometown was destroyed by a dragon. He doesn't want any trouble — but it finds them anyway.

Heian-kyō, capital and the center of elegant, aristocratic culture, is heavily guarded by a spiritual force field -- or so it seems. In reality, onmyōji (court magi who create the spiritual force field) can only defend the palace located in the northern part of the city; in downtown, monsters known as "horror" that feast upon human souls roam after sunset. There are, however, a group of heroes protecting commoners from "horrors" in darkness.