It's Hirasawa Yui's first year in high school, and she's eagerly searching for a club to join. At the same time, Tainaka Ritsu, a drummer, and her friend Akiyama Mio, a bass player, are desperately trying to save the school's light music club, which is about to be disbanded due to lack of members. They manage to recruit Kotobuki Tsumugi to play the keyboard, meaning they only need one more member to get the club running again. Yui joins, thinking it will be an easy experience for her to play the castanets, the only instrument she knows. However, the other members think their new addition is actually a guitar prodigy...