"Gekijōban Argonavis: Ryūsei no Obligato" is a film adaptation of the multimedia project "Argonavis from BanG Dream!" and serves as a prequel to the anime series. The story centers on the formation and struggles of the band Argonavis, a group of young musicians striving to make their mark in the competitive world of rock music. The narrative begins with Ren Nanahoshi, a reserved and introspective university student, who encounters the charismatic and passionate guitarist Yuto Goryo during a live performance. Inspired by Yuto's energy and the power of music, Ren decides to step out of his comfort zone and join forces with him to form a band.

As the band takes shape, additional members are introduced: Wataru Matoba, a cheerful and optimistic bassist; Banri Shiroishi, a disciplined and serious drummer; and Rio Kikyo, a skilled keyboardist with a calm and analytical demeanor. Each member brings their unique personality and musical background to the group, creating a dynamic yet occasionally tense environment as they navigate their differences and learn to collaborate. The band's journey is marked by their determination to refine their sound, overcome personal challenges, and connect with their audience through their music.

The central conflict arises as Argonavis prepares for a major competition, the "Ryūsei no Obligato," which serves as a platform for emerging bands to showcase their talent. The pressure to succeed intensifies as the band members confront their insecurities and past struggles, including Ren's self-doubt, Yuto's fear of failure, and the group's collective uncertainty about their future. Through rehearsals, performances, and heartfelt conversations, the band gradually strengthens their bond and hones their craft, culminating in a climactic performance that tests their resolve and unity.

The film explores themes of self-discovery, perseverance, and the transformative power of music, emphasizing the importance of collaboration and mutual support in achieving one's dreams. The characters' growth is portrayed through their interactions and the evolution of their music, reflecting their journey from individual musicians to a cohesive band. "Gekijōban Argonavis: Ryūsei no Obligato" provides a foundational narrative for the Argonavis project, setting the stage for their continued adventures and musical endeavors in subsequent media.