A thousand years after the deification, the Sage of the截教 (Jie Jiao) has confined himself in the Biyou Palace, bringing peace to the three realms. At this time, the ancient Buddha Lian Deng has not yet passed away, and Shakyamuni has not yet been born. The Western Paradise has not yet been established. At this time, Zhu Bajie is still the Celestial Marshal Tianpeng, the Monkey is still a stone, the Golden Cudgel is still the Sea-Stabilizing Needle, and even the Golden Cicada is just a cicada. The Master of the Biyou Palace, Tongtian, has quietly embarked on a wondrous journey, swapping bodies daily with Xu Ji, a modern convenience store owner. Thus, modern society has a Primordial Great Sage, while the chaotic three realms have an ignorant, clueless human with the body of a sage and countless innate treasures.