Yui Hirasawa's younger sister, she's much more responsible than Yui.
Ui's parents are rarely home, so she often takes herself to do the household chores and jobs. She is much more responsible, smart, and mature than her older sister. She is a third year junior student, and later she enters the same school her sister is in. She is a very talented guitar player, and takes pride in her aptitude. She enjoys teaching Yui sometimes, and also enjoys playing in her band. Ui's name means kind and considerate, because that is what she is. She tries helping all kinds of people and learn new concepts, and she is very good at it. She and her sister look very similar, but there is an age difference between them. By the end of the series, Ui joins the Light Music Club.