Rikuo is the grandson of Nurarihyon thus becoming the third heir of the Nura clan, but he has not started acting like the third heir. All the yokai want him to be the Third Heir, but he just wants to be a normal human.

Rikuo is taken ill following the overuse of his powers. Tsurara is nursing him back to health when his friends visit. Kana is confused about the nature of the relationship between Rikuo and Tsurara. Kiyojyuji informs Rikuo that they are going on a trip. Once they reach their destination Rikuo learns that the mountain is the domain of Gyuki. A member of his clan and the person responsible for trying kill Rikuo.

In order to defeat the powerful Abe no Seimei, the Nura clan yokai and Tono yokai entrust their power of a Hundred Demons to Rikuo.