Always looking for fun, Yui is fearless; anxiety and stage fright are unknown to her. She likes everything cute and makes a lot of physical contact with others like holding hands or hugging. She loves everything sweet, so she's energized by the sweets that Mugi brings, and her physical constitution is such that she does not gain weight no matter how much she eats. She can't stand being hot or cold, so she spends the winter under the kotatsu and rolls around on the floor in the summer in front of the fan, to keep cool. Yui is rather lazy, so her grades are always on the verge of failing except for fine arts, in which she is exceeding; sometimes she is the only person in her class who needs to retake a test, other times she manages to avoid failing all of her subjects by a one point margin. She has an average figure. Yui lives in a family of four with her younger sister Ui and both parents. Her parents are a "lovey-dovey" couple and often go on trips together, leaving both daughters behind. Having misunderstood that "light music" equals to "easy music" (like whistling), Yui joined the Light Music Club and picked up the guitar with absolutely no prior experience. She cannot do more than one thing at a time, but to make up for that she can be highly focused on a particular subject and once started, can advance quite substantially. However, whenever she learns something, she forgets something else. Yui is the type of person who doesn't read manuals and relies on her own intuition and self-taught approaches. She also does not remember any musical terminology. She possesses perfect pitch and is musically gifted, being able to tune her guitar without a tuner, but she does not appear to make the best of her ability. Yui is relatively determined and competitive, but at the same time she feels comfortable depending on the help of a few good friends like Ui, Nodoka, Mio and Azusa. The fluffiest hair in the game.