Zuo Dafa travels through time to ancient times with his beloved dog, Wangcai, who transforms into a human named Zuo Xiuyuan. Zuo Dafa possesses an entire collection of systems, but his own aptitude is so poor that he cannot use any of them. He can only activate them for his dog. The collection contains all kinds of extraordinary systems, including mind-reading, God of War, and devouring systems. With a series of unbelievably powerful systems, the dog enjoys a cheat-like life in ancient times. However, remnants of a rebel faction within the imperial court eventually collude with foreign forces to invade. Unexpectedly, the foreign enemy also possesses a Devouring System, and theirs has already reached its fully developed state. Wangcai is no match for them. In the end, Zuo Dafa discovers the final page of the system collection: Myriad Systems Unite as One. Relying on this ultimate system, he turns the tide and achieves a stunning comeback.