Nura

A supernatural saga of a 13-year-old by day, and a leader of a demon clan by night-straight from the pages of Weekly Shonen Jump!

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 grew up in a house full of yokai, so he always thought they were cool. But the kids in his class talk about yokai like they're bad! When his grandfather announces Rikuo as his chosen heir to run the Nura clan, Rikuo is torn between his human nature and his duties as a yokai. The rest of the clan's not so crazy about a wimpy part-human as their ruler, particularly Gagoze, a high-ranking yokai who would rather eat a human than be ruled by one.