Kumi Mashiba

She is beautiful, with short brown hair and dark eyes, and she is also short, unlike her brother.

Unlike her brother, Ryou Mashiba, Kumi is quite cheerful and beautiful. She first appears as a high school student and attracts the attention of many boys. However, her overprotective brother scares most of them away, resulting in her being single throughout her school years. She dislikes boxing, but seems to have come to terms with it after Ippo and Mashiba's fight, during which she also met Makunouchi Ippo. Afterwards, she disappeared for a while, but reappeared as a nurse after Ippo's fight with Volg Zangief. As a nurse, she often worries about Ippo's and others' wounds and even occasionally examines Ippo after his fights.

After meeting Ippo, her attitude toward boxing has calmed considerably, but she still retains a fundamental desire for him and her brother to retire. She and Ippo love each other, but Ippo's clumsy nature and stubbornness hinder their relationship, as do the numerous interventions of Nanako and Mari Iimura. Nanako, in particular, intentionally interrupts their time together, often claiming to be looking for Itagaki or simply suddenly noticing them while passing by.