Jack is a former heavyweight boxer from Little Ursa, now a boxing coach, and a pianist on the side. Deeply shaken by sending a fellow boxer into a coma, Jack quit life in the circuit and turned to piano playing, remaining inactive until Turbo Vulpe and his friends came along. He has since regained confidence in himself, and has taken on a selection of boxing proteges. Jack is kind, mellow, and slow to anger, but immensely strong and terrible to behold when angry. At first, he had doubts in being able to control his strength, but thanks to his new friends, was able to find a proper middle ground, and even helped train Syren Aquas in martial arts. Jack is deeply devoted to his wife, Tessie, and hopes to be a father someday.