|Played by||Yuiko Sasaki|
Yumi is shown as the stereotypical bad girlfriend of Japanese society: carnivorous, materialistic, greedy, and was only in a relationship with Kawahara for the benefits. She is very amoral, as even after Kawahara told her that he just found the money encouraged him to keep it so that they would live a lavish lifestyle.
Yumi during a date with Kawahara was planning on breaking up with him as her use for him was being used up. But when Kawahara offered to buy her a ring with all of the money he found, Yumi encouraged him to continue lavish spending to the point of marrying him and buying a mansion. Honey however came in during the ceremony talking Kawahara out of keeping the money. Yumi protested but Kawahara went ahead with the ceremony being called off.