Sabu

Sabu is the older brother of Rikiya

A long time ago, his owner put tatoos on him because he somehow thought it'd make his enemies easier to defeat. This, for some bizarre reason, caused Sabu to be rumored as a heavy-weight champion wolf who's (who is) teeth can crush the bones of his enemies if he's in a rage during a fight. A few weeks later, Sabu got fed up with the rumor and started killing his enemies in fights.

His rage was so deadly, that his surviving enemies swore to never fight him again, but one day when he was just about to kill his little brother's first enemy, Hakuro Yasunari, he made such a mess that he was banned from the ring.