Ui Hirasawa  

, 平沢 憂

Yui's younger sister, Ui, starts off as a third-year junior high school student but later joins Yui at the same high school the next year in the same class as Azusa. While she is one year younger than Yui, Ui is mature and responsible, taking care of household chores with ease. Despite this, she shares a strong bond with her older sister and has immense love and respect for her. Her physical appearance closely resembles Yui, even managing to fool the club once. Ui possesses some musical talent, particularly on the guitar, becoming capable of playing with the light music club band in just a few days after practicing (Yui was sick, so Ui dressed up as her). She takes great care of Yui and is willing to put her own health at risk to look after her. Ui is known as the ultimate groupie for Yui's band and supports them wholeheartedly. Occasionally, she contributes to the story narrative. Ui and Azusa are classmates and hang out together on occasion.