The anime project began when character designer Kerorira, a huge fan of the original manga, privately asked CloverWorks producer Shota Umehara if an adaptation was in the works; it turned out Aniplex staffer Mikihiro Takayama had coincidentally just pitched the same idea, so Umehara's team volunteered to produce it.

Director Saito Keiichiro, taking on his first TV anime directing job, was brought aboard specifically because Kerorira wanted to work with him, and Umehara knew him from prior collaborations.

Voice actress Aoyama Yoshino, cast as protagonist Hitori Gotoh, realized during preparation that she had been a socially withdrawn 'inkyara' in her own school days and chose not to consciously act out the trait, instead portraying her authentic past self.

For the role of Kita Ikuyo, a singing test was held in addition to the usual audition, since the character required both a 'Kita-like' personality and genuine singing ability; original manga author Hamaji Aki personally weighed in whenever staff opinions differed on casting.

Kerorira, who did the character designs and served as chief animation supervisor, also personally drew key animation for every single episode, contributing about 600 cuts total across the season—far more than the roughly 100 cuts a typical animator handles even across multiple episodes.

For the tense, poorly-played band performance in episode 8's live scene, the musicians first recorded a perfect take and then deliberately recorded a second, intentionally imperfect take, with the drummer specifically asked to rush or drag the rhythm to simulate nervous mistakes.

For the finale's song 'Seiza ni Naretara,' the guitar was actually restrung with one string cut before recording, to authentically replicate the scene where Hitori's guitar string snaps mid-performance; the arrangement was written so the song could still be completed without that string after the solo.

The ending cover song 'Korogaru Iwa, Kimi ni Asa ga Furu' by ASIAN KUNG-FU GENERATION (whose songs inspired the band members' names) was personally chosen by manga author Hamaji Aki, who had said even before the anime existed that this was the song she'd want the fictional band to cover.

Despite being a low-key rerelease compilation shown in only 132 domestic theaters, the first theatrical compilation film 'Re:' topped Japan's weekend box office rankings in both attendance and revenue upon release in June 2024.

The anime's promotion deliberately avoided releasing hype material for nearly a year, withholding new promotional videos and in-show music until after episodes aired, so that most story and song reveals hit audiences in real time rather than through pre-release previews.