Yui is the main character in K-ON!. She is a clumsy and immature girl who gets poor grades unless she really, really concentrates. Her younger sister, Ui, is much more mature and she takes care of Yui at home. She is prone to forgetting things very easily. Yui is a skilled guitar player and is able to perfectly tune her Gibson Les Paul guitar (nicknamed "Gitah") using only her ears. She also has a great voice and is very energetic during performances.

Yui: "Hello!"