Danpei Tange  

, 丹下 段平

Danpei is Joe's serious, cautious, and responsible mentor who introduces him to the world of boxing. He enjoys sake and becomes very cheerful when drunk, which contrasts with his strict personality in everyday life. Despite his polite demeanor when speaking to people of higher rank, this behavior annoys Joe, who doesn't care about such formalities. Before meeting Joe, it is revealed that Danpei was once a boxer himself but had to give up on his career after losing one of his eyes. He then decided to become a coach and trained his boxers with great passion and intensity. However, due to his strict approach, many of his trainees left him for better gyms, leaving him jobless and homeless. After meeting Joe and recognizing his potential in the sport, Danpei gives up drinking and vows to train him to become Japan's or even the world's best boxer, hoping for a brighter future for both of them.