Mountain Bison is a Hokkaido Wolf.
He is mainly white but has black stripes on his face. His back and ears are also black. He has fluffy cheeks and a scruffy hairtuft on his forehead.
In Meteor Gin, he is described as looking unusual for a wolf.
Ginga Nagareboshi Gin
He awaits Gin's groups arrival with Black Snake. He never fights and his technique isn't seen because Juga interrupts the fight between the two groups before it's his turn.
He is not seen again after this and likely died during the earthquake which destroyed the Underworld.
See more pictures in Mountain Bison/Gallery.