Hiro is a young boy that had some kind of injury that caused him to lose his memory. He returns home from the hospital but doesn't immediately remember his Pokémon.
Worried about the lonely-looking Pokémon, Hiro enters his room clutching his handmade badge, and sees a Yamikarasu outside the window. Not being able to remember anything, Hiro hastily chases it away and looks around the room, where he sees a pile of photos of himself with the Hinoarashi.
That night, feeling a sudden sense of foreboding, Hiro and his friends go into the forest, where they find a wounded Yamikarasu and his secret base. Hanging around Yamikarasu's neck is a handmade badge that Hiro made. He rescues it from a group of Nyarth and he begins to regain his memories.