A wanted man and a pacifist doctor chase an impossible cure across a rust-eaten world, and the show treats their partnership like it matters more than saving the country. The action flies with genuine invention, arrows that bloom into obstacles, a giant crab that isn't comic relief, landscapes that feel actively hostile. This is adventure that knows rust consumes everything, including hope, and builds something alive anyway.

Japan has been reduced to endless sandy wasteland by an apocalyptic event, and a rusting disease carried on the Rusting Winds threatens what remains of humanity. The government blames spreaders of mushroom spores like Bisco Akaboshi, a wanted criminal and skilled archer branded the Man-Eating Mushroom. In truth he is a hotheaded Mushroom Protector hunting for Sabikui, a legendary mushroom said to eat away rust and cure the disease, which he needs to save his master. Riding with him are his giant crab Akutagawa and Milo Nekoyanagi, a kind young doctor seeking a treatment for his sick sister. Facing prejudice from ordinary people, Bisco presses on across the wasteland in this action fantasy adventure.