Kumi Mashiba - 間柴 久美
Is Ryo Mashiba's sweet-natured, but hard-working and willful younger sister, and as such understands him better than anyone else. She will do almost anything to support her brother and make him happy, including going to his matches even though she doesn't like to see him get hurt. Ippo becomes infatuated with her early on, but didn't have a chance to tell her until more than a year later, when they met in an hospital as patient and nurse some months after the Ippo/Mashiba ring. They become friends and Kumi comes to like Ippo back, but their relationship tends to suffer from their friends' and relatives' constant interference, and also was somewhat strained after Ippo thought she was smitten with Dr. Sanada, until Kumi herself clarified the mistake after their match but didn't get a chance to say that Ippo was the one she really loved. Kumi tends to be modest and shy, but she will stand up for her brother and friends at a moment's notice. Voiced by: Sanae Kob...