Yamper is the reliable big brother of Pokémon in Cerise Park and solves the troubles that occur in the park brilliantly, but this time he notices that the water of the river flowing through the park is dirty, For the Pokémon that live by the water, a... (more)long with Ash, Goh and Chloe, they try to find out the cause of the dirt... Can Yamper protect the peace of Cerise Park?