Hiroko started running the fishing business after her husband, Makunouchi Kazuo, died. Since Kazuo's death, Hiroko tried to get into dating again, however, nobody sparked her interest. The men thought she would be alone, but she believed she was never alone since she has her son, Makunouchi Ippo.
As Makunouchi Ippo comes home from school, Hiroko notices he got beat up by students again. When Ippo got accepted to the gym and about to leave the gym for a spar, Hiroko suggests to think of his opponent as a fish, like his father used to. Before Ippo's debut match, Hiroko makes a big meal for him and tells him that she can't come because of work. Sometime before Ippo's debut match, Ippo asked her to put his name on his new trunks, but gave her an incorrect spelling ("IPO"), which he ended up wearing anyways, since it was too late when he noticed.
At home, Ippo asks Hiroko if she could come see him fight, Hiroko responds that she doesn't want to see her son get hit. Ippo is worried that Hiroko is doing too much work, when Ippo is asked to go to outdoor camp, Hiroko lets him go.
She is a very kind and strong-willed woman who cares for her son a great deal. Though she refuses to attend any of Ippo's matches because she doesn't want to watch him get hurt, she supports his boxing wholeheartedly because she knows how much joy it has brought to his life and how it has helped him with his self-esteem. She also would always know when Ippo would hide his tears when he came home from school when something happened to him.
- "You want me to come and watch you get punched? ...I'll definitely come when you won't get punched at all." - Episode 14, when Ippo asked her to come to one of his matches (to which Ippo thought, "That's impossible.")