Oops! I'm the Goddess' Dog?!

The girl who adopts the stray dog is the one her family calls a jinx, graded F-rank and laughed at as a failure by everyone around her. Inside the dog is a man who crossed over into a world ruled by beast tamers and woke up in the body of the lowest sort of mongrel. At his most hopeless he bound himself to a system that lets him evolve without limit, the catch being that the evolution runs on closeness with whoever holds his contract. Every bit of affection between him and the girl pushes him up a level. He decides to repay her by getting her through the beast tamer tournament. He starts out as a plain mutt. Through the closeness mechanic he awakens the bloodlines of the ancient beasts Qiongqi, Tengshe and Yinglong one after another, and he learns to take a human shape so he can stay beside her as a humanoid battle pet. The two of them fight their way through the feuds between the great houses and take the tournament title. The win pulls them into a plan by the Netherworld clan to destroy the world. Her family turns on her, a rival house works against her in secret, and the Netherworld Emperor himself descends.