Makoto wants to become a Tosa dog fighting trainer. His sumo Father Rouou gets him a brown puppy, but is it really a Tosa? Makoto finds out in shock that his dog is not a Tosa, but in fact a Siberian Wolf, but decides to make his dog "Zero" a fighting dog. But Makoto does not know that Zero's mother had been killed by Anzai's Yokozuna Tosa "Unryū" right in front of him, and he competes in the showring with the sole intention of getting revenge on Unryū.

(Source: Wikipedia)