>>28906763She has a younger sister named Ui, who is very mature and acts as the "older sister" of Yui, taking care of her and keeping her in line.[2] Yui works extremely hard to get better at playing guitar. During performances, Yui plays with amazing energy and joy which usually results in great response from the audience.[7][8][9]
Yui is the band's main vocalist and lead guitarist and has absolute pitch—she can tune her guitar perfectly without a tuner, which greatly impresses Azusa, who has played the guitar much longer than Yui.[6][10] She has a very easy-going nature, but has incredible focus and retention when she has a clear goal in sight; unfortunately this is limited to only one subject at a time, and her other skills deteriorate quickly (for example, Yui is at one point pressed to make up failing test scores, and she quickly brings her math skills up to par while allowing her guitar skills to deteriorate.)