Keiko began training as an idol during her last year of junior high in attempt to make herself "cuter", in contrast to her somewhat harsh outer-shell. After joining Elle she's began to come to terms with herself and not try to change for other people. Because of both her physical appearance and position on the student council, she is often mistaken for the student council president Kubo Harumi. She expresses her goal to become student council president during her 3rd year and looks up to Harumi greatly, so she often becomes flustered at the comparison. Keiko has a tendency to talk sternly and is quite upfront with her words, which leads people to believe that she is a 3rd year more often than a 1st year student.

Keiko is an only child and when compared to her parents, it's obvious where her demeanor came from. Though she thinks logically and usually keeps up the front of a girl too mature for her age, her secret sense of humor and sarcasm peek through when with her friends, revealing that in reality; she's not as uptight as some may say. She tends to be the most organized of the group despite being the youngest, many of her older groupmates coming to her for schedules or other paperwork that may have needed done. With all the stress that her responsibilities are bound to cause, she has to find ways to let loose some and one of those is karaoke!