Ui Hirasawa is a supportive and responsible character from the anime series K-On!. She is the younger sister of Yui Hirasawa, the protagonist of the series. Unlike her sister, Ui is mature, diligent, and reliable, often taking care of household chores and looking after Yui. Her caring nature and organizational skills make her an indispensable support for the Light Music Club, even though she is not an official member. Ui occasionally helps the club with their performances and practices, demonstrating her own musical talent. Her presence adds warmth and balance to the series.