This section is devoted to the small but important supporting characters that appear throughout One Pound Gospel. They often play key roles in the stories in which they appear.
| Ishida |
 Ishida is the much-put-upon trainer at Mukoda's Gym. While Mukoda is busy focusing on Hatanaka, Ishida trains the rest of the boxers. He is strict, but knows that where Kosaku is involved he has to be. When Coach Mukoda gives up on Kosaku, it's Ishida that sees him through his training in his match against Matsuzaka. |
| Shunpei |
 Kosaku isn't the only boxer Mukaida's Gym produces. Boys from all over Tokyo have joined up with Mukaida in hopes of pursuing their dreams of entering the professional ring and having their names recorded in the annuls of boxing history. As in all of Takahashi's series, the main character will usually have a group of friends he hangs out with, and Kosaku is no exception. Frequently he can be seen sparring with Shunpei (curly hair) and an unnamed boxer with straight hair. They do their best to keep him from over-eating, but have become frustrated with his lack of discipline, even though they recognize that he has been blessed with enormous punching power. |
| Saint Mary's Nuns |
 The flock of nuns that are seen with Mother Abbess and Angela at St. Mary's. Whenever Kosaku steps over the line they are ready to jump between he and Sister Angela. There are three nuns that can usually be seen in the background, one with glasses, a thin-faced woman, and a chubby faced nun. |
| Amakusa's Coach |
 Amakusa's coach is a seasoned professional who is confident that his boxer will have little trouble defeating Kosaku. |
| Kurusu's Friend |
 Friends since childhood, she has always done her best to look after Kurusu. Even though she refuses to admit it, she has feelings for him, and only wants to see him suceed in life. She was the one that encouraged him to become a boxer in hopes that it would instill confidence in him. |
| Tsukuda |
 Even Onimaru's own coach has given up on him. Out of desperation he turns to Mukoda in hopes of talking Kosaku into a match with his boxer. |
| Onimaru's Wife |
 Like everyone else in Onimaru's life his wife has given up on her husbands dream of becoming a world-class boxer. She's ready for him to retire and help take care of the child they are about to have. |
| Tsuboi |
 During a vacation to Mexico, Tsuboi got incredibly drunk on Tequila and met Xavier Fernandez. Tsuboi thought he had met a professional boxer, but in reality Fernandez had only had one match. Bringing him back to Japan, Tsuboi renamed him Takos Hachiro and sets him up in an eight-round match against Kosaku Hatanaka. |
| Yoshihiko's Uncle |
 Tired of dealing with Masahiko's antics, his uncle and former coach decides to dump his bratty nephew on Mukoda's Gym. |
| Yoshihiko's Parents |
 Masahiko's simple but rich parents laughingly go along with their son's dream of moving to Tokyo and learning how to be a boxer. |
| Calorie Cottage Owner |
 The owner of the Calorie Cottage, a local restaurant that Kosaku works for. The owner is eager to support Kosaku's dreams of becoming a chef and encourages him to give up boxing and take over the kitchen of his restaurant. |
| Manabu's Coach |
 Manabu's coach doesn't exactly have high hopes for the teacher turned boxer. In fact he thinks it would be safer if Sakura would just quit rather than continue with his boxing career. |
| Morishita |
 Wakaoji's much put-upon assistant chef, who in all actuality is a much better chef than Wakaoji. |
| Angela's Father |
 Angela's father is a kind man who is supportive of his daughter's choices, however he seems oblivious to Angela's Aunt's manipulations. |
| Angela's Mother |
 Like her husband Angela's mother seems to have no qualms about her daughter's decision to become a nun. |
