Like Michiru, Sayuki attends the same school as Yumiko. She very athletic and has always excelled in sports: when she entered high school, she joined the racing club and her performance is well known among students. However, her aptitude to physical activities is compensated by only average skills in intellectual disciplines. Sayuki is well aware of this and doesn’t like the stereotype, so she started wearing glasses to give herself a more intelligent appearance.
Sayuki is very easy-going and relaxed, and often quarrels with Michiru when their attitudes collide, but mostly in a joking way. While not as attached to Yumiko as Michiru, to her the girl is still her best friend.