Kotobuki Tsumugi, often referred to as Mugi, is a key character in the anime series K-On!. She is a bright and gentle high school student with a passion for music and tea. Mugi is part of the light music club and plays the keyboard, contributing her elegant sound to the group's performances. Despite her wealthy background, she remains humble and develops strong friendships with her bandmates. Mugi's love for baking and preparing delightful snacks for the group showcases her nurturing side. Her polite demeanor and reserved nature often hide a whimsical sense of fun, making her a beloved character in the series.