Shi Er Chang Sheng

After the battle between the demons and the gods, Yin Long, one of the gods, voluntarily entered the world of reincarnation and reincarnated as the girl Shi Er. Pan Gu, one of the demons, fell in that battle, and his soul split into twelve pieces, incarnating into twelve magical beasts, and his body turned into mountains and rivers.
Years later, Pan Gu incarnated in a new body as Chang Sheng meets Shi Er on his way and sets off on a long journey to find the twelve shard beasts of his former spirit.
(Source: Neko_Mama_8o8 at MDL)