Deeply shy and socially awkward high school freshman Yoshino Nagawa has never had a proper friend. On her first day at Minami Matsumoto High School, her crippling communication skills fail her yet again, forcing her to flee into a bathroom stall to escape the overwhelming situation. As she hides, she unconsciously hums a rock song under her breath. Her voice, heard through the stall door, is overheard by another first-year student named Futaba Shirase, who is immediately captivated.

Futaba, a remarkably sociable and talented girl who works at her family's inn, is determined to start a band. She recruits Yoshino as the vocalist and quickly gathers two other members to form a punk rock club. Luna Fujimori, a former competitive swimmer who is now a truant with a deep knowledge of music, becomes the bassist. Kanae Sakanoshita, a bright and somewhat narcissistic girl who was rejected from the school's light music club, rounds out the group on guitar.

Set in the city of Matsumoto in Nagano Prefecture, the story follows the four members of the Punk Rock Club as they navigate the chaotic path to forming a real band. They face the immediate challenge of gaining official club status to secure a rehearsal space, clashing with the more conventional Light Music Club in the process. The narrative is driven by their struggles with self-doubt, individual quirks, and the technical demands of learning instruments, all while balancing their regular school lives. Key arcs include their frantic preparations for the school's music festival and the production of their first music video, moments that highlight their growing camaraderie and the cathartic power of their music. The series balances slapstick comedy and musical passion with genuine character development, exploring how four misfit girls find connection, confidence, and their own voices through the explosive energy of rock and punk.