Hiori is a young boy who has a secret identity called "Mysterious thief Pokemon 7". He goes around taking stolen items, and return them to their rightful owner. This is the story of him and his adventures.

The story tells about Shu, the main character (who at first, as beginner, is only Pikachu's master) and his Pokémon's travel through the country to improve their few fighting abilities; but, differently from all the other masters, they can understand each other thanks to a special earphone.
We follow Shu and his companion through a lot of very funny adventures which will bring the boy to catch new Pokémon and to become a very experienced Pokémon master.