In an ancient Japan long at peace, the evil samurai warlord Ashida returns and begins using forbidden Kuji magic to transform the forest's animals into an army of deadly samurai. From their home atop Ninja Mountain, a wise master sends his students to investigate, but one by one they are captured, leaving only the youngest and most gifted ninja, Hiro, and his strong but clumsy friend Futo to set out after them. Wielding Kuji spells of his own, Hiro journeys across the wilderness to rescue his fellow ninjas, free the enchanted animals, and stop Ashida before his dark power engulfs the land.