Knuckle is a mixed breed, subordinate of Liger. Like Liger, he too was a hunting dog whose human was killed by the bears and then got wild, joining Liger, who had his same life goals: to kill the bears to avenge his owner. He was with Liger when the latter met Koyuki and Kotetsu, warning them about the roaming bears when they get surprised by one of these. Liger and Knuckle, with another packmate, follow the bear but get wounded on his back. Thanks to Weed, the three dogs get carried to Joe's owner Ninomya, who heals them. Once fine, the three follow Joe and fight against the Hybrid Grizzly Bear.

Unfortunately, Knuckle gets crushed under the Hybrid Grizzly bear's paws, as he tries to make an attack.