As the future emperor of the African jungle, Leo the lion cub is sent off to live with a little Japanese boy named Kenichi. During his stint with the humans, Leo has many learning experiences and somehow always manages to get into a little trouble along the way. But when a rat arrives—carried by a stork like a little bundle of joy, no less—with a message from home, Leo realizes it's time to return to the jungle. As he embarks on his biggest adventure yet, he's unaware of the great battles that lie ahead.