Starting with Three Tails, I Grind to Nine Tails and Become Invincible

The great tribulation approaches, and the nine-tailed fox clan is wiped out overnight. Su Heng transmigrates into a three-tailed remnant fox and, at the brink of death, awakens the [Supreme Hiding System]—the deeper you hide, the greater the rewards; if you actively expose yourself, the system resets and you die on the spot. He hides in a wolf's belly to evade the demon court's search, lies in a pile of corpses to witness celestial immortals hunting, and jumps into an underground river to escape from a Taiyi Golden Immortal's claws. Hiding becomes his only way to survive. But as he hides, the fox king's inheritance falls into his hands, his fourth tail grows, and even the head of the Fox Hunting Division, Jin Ling, declares: 'Three days later, I'll be waiting for you at the mine.' So he goes. He infiltrates the demon court to steal the demon emperor's secrets, poses as a barbarian guest to provoke the witch-demon war, hides in Kunlun during the Investiture of the Gods to scheme against Tongtian Jiaozhu, and on the Journey to the West, transforms into a fox demon to secretly control the eighty-one tribulations. From start to finish, he's in every major battle, yet no one ever knows he exists. The day his nine tails fully emerge, he attains sainthood. Only then does the world realize—the biggest winner of the tribulation has always been the fox hiding in the shadows. — Description from novelcodex.org