Kojūrō was the oldest known canine member of the Kurohabaki Clan.
Ginga Densetsu Weed: Orion
He was tasked with being the guardian and mentor of the young Yamabiko, Kurohabaki Terumune's son. He left with the puppy to Shikoku, away from Yamabiko's evil and dangerous brother, Kurohabaki Masamune.
After Orion and his group save Yamabiko from Masamune's assassins, Kojūrō thanks them and they become friends. He tells them that they are members of the Kurohabaki clan, making Heizō and Tyson become nervous. Kojūrō then explains the conflict between Terumune and Masamune. Soon after, Kojūrō bids them farewell, and he and Yamabiko head for Shikoku.
Later, Kojūrō had attempted to give up Yamabiko to Masamune, which almost got him completely banished from Ouu. When he meets with Masamune, he has a change of heart and attempts to attack him. He and Masamune fight, but Kojūrō is blinded by the long scarf, preventing him from seeing Masamune's oncoming attack. Masamune injures the old dog, slicing his stomach open. Kojūrō collapses and dies from his severe injuries.