Yumi is bashful beyond words, very timid and unsure of herself. She first met Sachiko, the star of Lillian School, and had her tie fixed by Sachiko, which mortified Yumi. Yumi's friend, Tsutako Takeshima, took a cute picture of this and wanted to display it in the school festival. Tsutako gets Yumi to ask permission from Sachiko. Other characters often comment on how her emotions 'show on her face.