Dokuganryū is a light-coloured Tosa-inu with dark markings. He has a dark muzzle, dark ears and a dark coloured back. He often wears an eyepatch over his remaining eye, whilst his other is missing. His left eye has a vertical scar over it, which he got from his siblings when they fought.
When Dokuganryū was a puppy, he was the runt in his mother's large litter of seven puppies. His siblings would push and shove him away, not allowing him to get his fill of his mother's milk. One time when one of the other puppies loosened its grip on its mother's teat, Dokuganryū quickly ran and took it before the other could get a good grip.
The other puppy got angry and began to bite Dokuganryū's ear and attempt to pull him off. Soon the other puppies joined in to fight him. When the owner was away he heard a bunch of noise coming from where the dogs were.
He ran to find that all of the puppies were bloody, beaten and sitting farther away from their mother while Dokuganryū, the smallest of them all suckled from his mother as they all watched. He didn't survive without paying a price, though. He got a slashed left eye in the fight with his siblings.
Dokuganryū's owner realized he had potential to become a great fighting dog and began training him by putting an eye patch over his good eye which had a very small slit inside, because of this Dokuganryū was able to develope very precise vision.
When his match with Zero began he had the upper hand, because Zero hesitated in his attacks when Dokuganryū didn't move when he charged him. He, on the other hand, ran with amazing speed, grabbing Zero by the neck and tossing him around the ring like a rag doll.
Eventually, Zero managed to get a hold of him and threw him against the bars of the ring, which split open his forehead, causing blood to run over his eye, clouding his vision. Zero thought it would blind the dog completely, but because of Dokuganryū's training even with the very limited vision, he was still able to fight with full strength.
Eventually Dokuganryū managed to pin Zero down after a long exhausting fight. The judge had already started the countdown and Zero began to recount all the reasons he was fighting. His mother, Kobushimaru, to fight Unryu and defeat him for all the things he had done.
Thinking about those things gave Zero the strength to roll over, despite the tight grip on his neck and do a push up which made the judge stop counting because the young wolf had risen to his feet. Dokuganryū was baffled by Zero's determination giving him a chance to grab the dog and throw him against the bars again.
All of a sudden Dokuganryū no longer believed he would be able to fight blind and began to furiously rub at his eye to get it clean. At this stage the owner threw in the towel, declaring Zero the victory.
- Dokuganryū's name is based on the alias of a Sengoku era samurai named Date Masamune