Thomas Oliver Gungsten is a 15-year-old teen who lost his family to a wild Pokémon stampede in his hometown of Kilyla City. Because of this, he has had a tremendous fear of Pokémon for years. But one fateful day, he meets a Buizel and Poochyena in trouble and saves them, earning their love. After some events, he is sent into the Pokémon world of Mystery Dungeon with Team Believers.