About me: a powerful demon with an immortal body only considering Tomoe to be his equal. However when Tomoe left him, he succumbed to the gods powers and lost his body. After being locked up, he was given a chance to live in a boy's body and took it, returning to the world and is constantly seeking a way to retrieve his lost body.
Akura-Ou, also known as Kirihito in his human form, or the evil king/ demon king, was an infamous yokai that has been living for at least 600 years. He worked with Tomoe, wrecking havoc to the world of both yokai and humans alike. They were so undefeatable that not even the gods of Izumo could overcome their combined power.
That was until Tomoe fell in love with a human woman known as Yukiji. After being captured by the gods, his soul was taken from his immortal body and he was sent to Yomi-no-Kuni and split, his soul sealed into a group of rocks whilst his immortal body thrown into eternal fiery flames.
He lived there for a long time until the soul of a young, recently-deceased, boy named Mori Kirihito came to him and asked him to send an 'I'm sorry' message to his mother because they had a silly argument just before his death. Akura-Ou accepted out of boredom and curiosity. Upon taking the boy's body he woke in a hospital room being hugged by 'his' mother.
After some time, Akura-ou created two fox-masked shikigami to help him retrieve his original body back from Yomi-no-Kuni.