It's Yui Hirasawa's first year in high school, and she's eagerly searching for a club to join. At the same time, Ritsu Tainaka, a drummer, and her friend Mio Akiyama, a bassist, 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 Tsumugi Kotobuki 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...
Bagi Yui Hirasawa kini di bangku sekolah tinggi buat tahun pertama, dia hendak cari kelab untuk ikut serta jua. Sementara, Ritsu Tainaka, seorang pemain dram, dan kawannya Mio Akiyama, penyanyi bes, cuba selamatkan kelab sekolah muzik ringan, yang hampir terbubar disebabkan kekurangan ahli. Mereka mampu merekrut Tsumugi Kotobuki untuk bermain papan nada, bermakna mereka hanya perlu seorang ahli lagi supaya kelab dikelolakan semula. Yui turut menyertainya, ingat pengalaman dirinya mahir untuk bermain kastanet, satu-satunya alat muzik dimainkan olehnya. Namun, anggota lain memikirkan tambahan baru mereka sebenarnya pemain gitar genius...