Makoto dreams of becoming a Tosa dog fighting instructor and is gifted a brown puppy by his sumo wrestler father, Rouou. But he is surprised to discover that the dog he received is not a Tosa, but a Siberian Wolf named Zero. Nevertheless, he resolves to train Zero as a fighting dog. What he doesn't know is that Zero's mother was murdered by Unryū, Anzai's Yokozuna Tosa, right before his eyes. Makoto enters Zero into various competitions with the sole intent of avenging Zero's mother by defeating Unryū.
