Unrivaled Chaos Emperor (Tales Of Ragnarok)

Kai runs away from his Yakuza family after being driven by a monster within to assault his classmates.

He gets mixed up with the devils of magical world meeting Kono of the Asmodeus Clan aka the Viol Dragon Emperor of Supremacy, the one destined to stand at the pinnacle of all races.

Kai sells his soul to rescue Yuri, a Fallen Angel that betrayed her own race to protect him. He regrets his decision when he falls in love at first sight with a devil named Katsumi Belial.

A massive 9 vs 1800 battle ensues where Kai discovers secrets about himself. That he's also in love with Yuri. That he's known about the magical side of the World since birth. And that he's been planning an awakening to free the monster within.