A kid with a cursed arm that wants to eat everything he touches has to figure out if he's still himself or if the thing inside him is already winning. The show doesn't waste time on "will he lose control", it starts from the assumption that he already has, and everything after that is just survival and small, brutal acts of defiance. Every fight is a negotiation between a person and a monster wearing his skin, and by episode three you stop asking which one is really talking.

Xia Qiu, the young master of the Shenzhao Sect, comes back to his homeland when his elder brother Xia Chun invites him, and soon stumbles on strange research hidden in a secret chamber. Wanting to learn what Xia Chun is hiding, he heads to Fuyu Pool, but his brother turns on him and forces him to serve as a sacrifice to Feilian, a ferocious ancient beast. Through a twist of fate, Feilian ends up living inside Xia Qiu's body, and he loses the powers he once had. A girl named Long Yan happens upon him and saves him. When he wakes, Qing Chou, acting head of the Long family, arranges for him to pose as Long Ze, the family's youngest son, and a new life and adventure begin. As Long Ze, he meets many companions along the way and slowly comes to know what familial love feels like.