Plot
The movie opens with a childhood scene of Honoka attempting to leap over a puddle, cheered on by Kotori and watched by Umi, symbolizing her determination to persevere.
Set after the second season, μ's (pronounced "muse") learns that the organizers of Love Live! are planning a third competition at the Akiba Dome. To help promote the event, μ's is invited to the United States for a TV feature. Though they have decided to disband after the third years graduate, they agree to perform as school idols until the end of the month.
While training and sightseeing in New York City, a montage set to "Hello, Hoshi o Kazoete" (Hello,星を数えて) plays. Honoka gets lost and meets a mysterious Japanese singer performing "As Time Goes By" (Japanese) / "Stars, Come to Me!" (International). The singer, who once performed with close friends but is now alone, encourages Honoka to reflect on why she sings. After safely guiding Honoka back, she disappears, leaving Honoka with her microphone and a lingering question: “Whose sake do you sing for?” The section ends with μ's performing "Angelic Angel" in Times Square and Central Park.
Back in Japan, μ's has become a nationwide phenomenon, as seen in the montage with "?← Heartbeat". Fans beg them to continue, and even Principal Minami hopes they will reinvent themselves rather than disband. Honoka struggles with the decision until A-Rise’s Tsubasa invites her for a late-night talk, suggesting μ's could follow A-Rise’s example and go pro.
Amid a rainstorm, Honoka again meets the mysterious singer, who asks if she has found her answer. Transported to a hill of flowers, Honoka is told she can "fly" whenever she chooses. Taking the leap, Honoka reaffirms her love for school idols. Meanwhile, Eli delivers the third years' decision to end μ's activities.
The next morning, Honoka and the others agree to one final act: a large-scale concert to celebrate all school idols. She pitches the idea to Tsubasa, who accepts. Despite mass emails, few idols respond, so μ's travels nationwide in groups of three to recruit them, with "Future Style" playing during the montage. Kotori and Anju collaborate on costumes, while Maki and Tsubasa work on the event’s main song. On the night before the festival, Honoka publicly announces μ's disbandment, leaving fans saddened.
On festival day, μ's races toward Akiba, with Honoka joyfully spinning and dancing as petals drift by, symbolizing her newfound freedom. At the venue, they find countless school idols gathered, all dressed in costumes inspired by μ's. The festival opens with “Sunny Day Song,” now embraced as the anthem for all school idols.
The film closes with a new school year at Otonokizaka High, where Yukiho and Alisa, now third years, carry on μ's' legacy as leaders of the Idol Research Club. In a flashback, μ's shares a quiet moment backstage before their last performance. The movie concludes with "Bokutachi wa Hitotsu no Hikari" (僕たちはひとつの光) at Akiba Dome, marking the group’s heartfelt farewell.