Tōbei Kirigakure (霧隠 藤兵衛 Kirigakure Toubei?) is Kotarō's father and a trained ninja. During his battle with the dark wizard Yaminorius III, he was turned into a dog via a powerful curse by the wizard. As a result of this, he was renamed Gonzales (ゴンザレス Gonzaresu?), or Gon for short, and adopted by his own family as a pet.
He serves as the mentor to the Ganba Team, being the only one who knows their true identities.