While the day belongs to humans, the night belongs to yokai, supernatural creatures that thrive on human fear. Caught between these worlds is Rikuo Nura. He's three-quarters human, but his grandfather is none other than Nurarihyon, the supreme commander of the Nura clan, a powerful yokai consortium. So, Rikuo is an ordinary teenager three quarters of the time, until his yokai blood awakens. Then Rikuo transforms into the future leader of the Nura clan, leading a hundred demons.

Rikuo's confrontation with the mutinous Gyuki reveals a schism within the Nura clan. Nurarihyon convenes an assembly to formally name Rikuo as the next leader. But Rikuo's willingness to pardon Gyuki for his crimes causes friction within the group. Some officers doubt that this thirteen-year-old can restore the weakening Nura clan to its former glory. Meanwhile, surprise attacks from increasingly powerful rival yokai continue.