Name: Koyuki
Japanese name: 小雪
Sex: Female
Breed: Kishu

Koyuki is a female pet dog. She was running around in the mountains to find her baby brother, Kotetsu, but got trapped in a hunter's trap. Weed comes to save her and she quickly feels attracked by the young dog.

She returns home where she talks to her half-sister Chako, who recently has met the Shiba, Sasuke. Together, they decide to go and search for them. They find Weed and Kotetsu in a battle with the stray Yuusuke and his gang. Afterwards she meets with Weed frequently, but soon Koyuki's owner sends her away to become a breeding dog. Weed follows the car and free Koyuki from her cage.

Together, they start a small journey together to be alone and care for their growing relationship. They visit Weed's mother's grave and Koyuki bury a fish near it. It's her way of paying respect. Shortly after, their little vacation is interrupted by Rocket who tells them of a growing threat in Hokkaido (the German Shepherd, Victor).

Weed now leaves Koyuki in care of her brother Kotetsu. Koyuki moors his departure, but understand that Weed has certain duties as leader of Ou.

In the Hybrid bear arc, Koyuki meets the red puppy Koujiro as Kotetsu hunts a small rabbit for his sister. Koujiro has killed Kotetsu's prey. As they discuss who the kill belongs to, they are ambushed by the Hybrid Grizzly bear. However, Koujiro's father is nearby and he, along with his pack mates, scares the bear off. Shortly after, Koyuki and her brother is reunited with Weed, who has come to search for them.

When the battle against the Hybrid bear begins, Koyuki is taken to safety in a cave along with Kotetsu and Koujiro. She survives the battle and reunites with her love, Weed.