Kuroryu is a Tosa who lives near the barrow Oscar lived in when he was a stray. He's a very aggressive fighting dog who kills if other dogs make fun of him whenever he's close to losing a fight. One day, he killed the young Akita who lived with him named Chikuma by using all of his front claws to slash down his belly. As a punishment, his owner covered his front paws with tape so he can't use his claws. Because of that, on the day he fought the Tosa, Takeru, he couldn't win the fight without losing his left eye and right ear. The murderer of Chikuma had been almost slaughtered by Takeru which gave him his owner's revenge.
He enters a match with Oscar and Kagura who defeat him in the first round, but in the second, he performs the Pou Supuritta to defeat Kagura. Oscar is outraged and in the third round, he gores Kuroryu's good eye and rips off his remaining ear which makes his owner change his name to Minikui which means "ugly." He also has to retreat from the arena forever.