Once demons and humans were at war, and special warriors were needed to defend humans. Now a peace treaty exists between demons and humans. To uphold this treaty, human warriors now protect allied demons from other, predatory demons.

The Yosogi family is given this thankless task--and its heir is young Akira, who can't even hold is own against his older sister. In their generation, hoever, only Akira can sense the presence of demons, so he must become the next Demon Defender. But their grandfather has brought in a shy girl named Matsuri--and Akira is warned in a dream he must protect her at all costs!