Nobumasa Sawabe

In the Forest of Okoya, Koko is a feral child who has been raised as a Pokémon by the Mythical Pokémon Zarude. Koko has grown up never doubting that he is a Pokémon even though he can't really use any sort of moves. Ash Ketchum and Pikachu meet Koko and help him protect the Great Tree from the crooked scientist Dr. Zed.

The film tells the story of interweaving friendships between three children and yo-kai. The film is set in 1960s Tokyo, in Sakura Motomachi. A boy named Shin lives a poor but happy life. When his mother — his only family member — dies, Shin's unhappiness hits rock bottom. That is when another boy named Itsuki saves Shin. Itsuki has also lost his older sister. Shin, Itsuki, and a young girl named Tae who can see yo-kai all become friends. Shin's guardian spirit Suu-san, a "Nekomata" cat, and other new yo-kai join their group, and this group is able to regain what it means to have a precious family. This new family must now face a mysterious incident, and a shocking reality awaits them.

When Lawrence III's scheme to capture the Legendary Pokémon Lugia upsets the balance of nature, it is up to Ash Ketchum and his friends to save the world.