Su Yi, a thirteen-year-old boy with a lazy temperament like a cat, and his partner Kailuo, a white cat with the same lazy temperament, and Xia Youer, traveled to different countries and cities in various eras, performing missions for an organization called "Eliminate Demon". In mission after mission and battle with various creatures, Su Yi gradually saw through the true face of the organization. And his mysterious life experience is slowly revealed. Having lost his parents since childhood, he was dependent on his only sister. However, during a mission, his sister died, and the power hidden in Su Yi's body finally exploded. And Xia Youer also expressed her feelings for Su Yi. No one knows what the outcome will be...