Celebi is a mysterious Pokemon, that can travel through time. While escaping from a Pokemon Thief, he transcends through time accidentally bringing a boy named Yukinari with him 40 years into the future. Ash and the gang meet Yukinari and Celebi and heard his story about traveling through time, but even 40 years in the future, there are still some who wants Celebi for themself. The Team Rocket's most powerful Pokemon Hunter - The Masked Vicious wants to capture Celebi for himself and he succeeds into capture him onto the Dark Ball - a Pokeball that makes every Pokemon evil. With Celebi at his hands, Vicious wants to be the ruler of the world, it's up to Ash and the gang to stop him and make Celebi back to his original self.