Four girls decide to join their school's club for “light music” (orchestral arrangements of classic and popular music usually used for “mood music”) in order to try and save the club from being closed by the school. The only problem? Not a one of them has any experience with music outside of listening to it.
High school has begun, and the club rush in underway. Ritsu convinces her friend Mio to apply with her to the light music club (by shredding her application to the literature club). They soon learn that all of the club's members graduated the previous year, so the club is up for suspension if four member don't join in a month. Ritsu and Mio set out to find two new members immediately by starting a band to draw attention.
Tsumugi is interested in the choir, and runs into the light music club while looking to join the choir. Ritsu quickly begins to beg Tsumugi to join, to which she agrees since Ritsu and Mio look like they are fun. Tsumugi signs on as the keyboard player.
Yui is a clumsy person of few interests. She likes tasty and cute things, and hasn't found a club to interest her yet. Near the end of the month probation, she stumbles upon a flyer for the light music club. She takes this to mean that she can play around with "easy" instruments like the castanets (which is the only instrument she knows how to play). Upon showing interest in the club, and falling in love with the food offered to her, she admits to Ritsu and the gang that she can't play a single instrument. Before she leaves, they ask her to listen to their performance. Reminiscent of Koyuki in BECK, Yui is highly enticed and excited by the music, and joins the club anyways, with the other members offering to teach her the guitar.