With just three days remaining until the closure of the 2004 Shiba High Holly Festival, a group of determined schoolgirls faces unexpected challenges as their band prepares for the final performance of their senior year. Their guitarist is sidelined due to a hand injury, and soon after, the singer resigns following a heated debate over the guitarist's replacement. Undeterred, the remaining members—keyboardist Kei, drummer Kyoko, and bassist Nozomi—decide to proceed with the rock concert at the festival, opting to cover songs by Blue Hearts, including the iconic "Linda Linda." To fill the void left by the singer, they enlist the help of a passing girl, Son, a Korean exchange student who struggles with Japanese.
The first day concludes with the girls dedicating themselves to learning their parts, while Son practices her singing at a karaoke parlor. Meanwhile, Kyoko finds herself caught in delightful conversation with her crush, Kazuya.
As the second day begins, the girls arrive at school early to maximize their practice time. Unfortunately, they mismanage their schedule and miss their allotted time slot. However, a glimmer of hope appears when Kei manages to reach out to her ex-boyfriend, Maezano, who graciously allows them to use his studio for practice. They hustle back to school late at night, where they continue to rehearse tirelessly into the early hours.
By the time morning dawns, their efforts bear fruit as Paranmaum shines through their rigorous rehearsals. The festival kicks off, and the girls split their time helping with class booths. While Kei works on her guitar parts and shares a brief chat with her rocker friend Takako, Son finds herself distracted, daydreaming about the band instead of attending to her duties at the culture exchange. Meanwhile, Kyoko sells delicious crepes, and Nozomi drifts off to sleep against her bass guitar in a classroom.
Awakening Nozomi from her slumber, Kei and Kyoko go to fetch Son, who faces an uncomfortable confession of affection from her classmate, Makihara. That evening, over dinner at Nozomi's home, the girls take a nostalgic trip down memory lane, encouraging Kyoko to muster the courage to speak to Kazuya before their performance the following day. Their night culminates in a return to school, where they ardently practice until the break of dawn.
On the crucial day of their performance, Paranmaum heads back to the studio for a final rehearsal. However, the exhaustion takes over, and they end up falling asleep. In her dreams, Kei envisions herself celebrated and performing for the Ramones and Pierre Taki at the renowned Nippon Budokan.
At school, their friends can’t locate the band, so to fill the void, Moe, the original guitarist of Paranmaum, and Takako entertain the crowd with impromptu renditions of "The Water is Wide" and a song by Unicorn. Suddenly, Kyoko is jolted awake by the ringing of her cell phone; it's Kazuya inquiring about her whereabouts. The band scrambles into a taxi amid the torrential downpour, racing against time to reach the performance stage. As they set up just moments before their due time, Kyoko finally encounters Kazuya, and in that electric moment, Son introduces the band as "Paranmaum." They delightfully launch into two of their planned tracks, "Linda Linda" and "Owaranai Uta," thrilling the audience as they embrace the magic of their performance.
