The 9-year-old human boy Lian (voiced by Aoi Miyazaki) lost his mother. He refused the care of his relatives and ran to the busy streets alone. He happened to meet the monster Kuma Tetsu (voiced by Hiroshi Yakusho) who came to the human world by chance to find a disciple. The Grand Master of the Monster World (voiced by Masahiko Tsukawa) is about to be reincarnated as a god. The candidate to take his place will be between Zhu Wangshan (voiced by Kazuhiro Yamaji) and Kuma Tetsu, but there is no direct disciple, which makes Kuma Tetsu hopeless. Taking this opportunity, Lian broke into the monster world. He and Kuma Tetsu quarreled constantly, but in the process of conflict, they seemed to gradually identify with each other. In the blink of an eye, Lian (played by Shota Sometani) has grown into a young man with strong martial arts. He accidentally returned to the human world and regained his long-lost identity and feelings. At the same time, the date to decide the Grand Master is approaching day by day, but an unexpected accident happened...