On September 8, 2020, IU uploaded a video of herself as Lee Ji-dong, her Edam Entertainment employee alter-ego, on her official YouTube channel, revealing that she would be releasing a studio album by the end of the year.
[6][7] While working on the album, IU revealed in an interview with W Korea that she did not feel the need to include a self-composed song, instead deciding to cut them as their calmer sound did not fit the tone of the rest of the record.
[8] She revealed that she wanted to make an album that was enjoyable and, at the same time, told stories, aiming to "put on a show that, above all, entertains."
She compared Lilac to a blockbuster rather than an independent film, concluding, "I wanted to make my world, which has always been small and safe, bigger and wider, even if it was a little risky.
"[12] "Lilac", which IU described as a bittersweet song reminiscent of a spring typhoon,[13] recalls the disco sound from the 1970s and the 1980s, harmonizing the bass line with funk and pop elements.
(Korean: 어쩜 이렇게 하늘은 더 바람은 또 완벽한 건지; RR: Eojjeom ireoke haneur-eun deo baram-eun tto wanbyeokhan geonji).
[16] In "Coin", based on the disco punk rhythms of the 70s and the 80s,[9] she asks to let her play one last round of a challenging game that is harmful to her health.
[16][18] "Celebrity" was born for a friend labelled eccentric for her personality and clothes and then expanded to a message for all those who have felt a sense of alienation for not having met expectations.
[16] "Empty Cup" is lo-fi and R&B,[16] telling of the moment in which one decides to give up the person by their side, nevertheless going on "unhappy, even resentful" because they are unable to end a relationship that has lasted so long.
"[27] IU compares her journey to the stormy sea, finding comfort in knowing her path that will always lead her back to her true self.
[11] "Ah Puh" is a hip hop track that conveys confidence, loneliness, and exhaustion, giving a fresh vibe with the repetition of some consonants and vowels.
[1] IU unveiled the track list on her official SNS accounts on March 10, revealing K-R&B singer Dean as a featured artist, with AKMU's Lee Chan-hyuk, singer-songwriter Naul, and Penomeco taking part in production.
[34] "Lilac" was simultaneously released alongside the album on March 25, 2021 as its second single and title track, also accompanied by a music video directed by Flipevil.
[43] Shim Yoon-ji of the Kyunghyang Shinmun felt that the "exciting yet lonely, lyrical yet ambiguous" lyrics revealed IU's strengths, and that, by recounting her growth through music, she had developed a record "that comforts young people who live in the contemporary age," concluding that the album's greatest characteristic was that it was "so different that it cannot be summarized in a single word.
While observing that it might seem "a composition that can be a bit cluttered because it feels like it contains various things without much calculation," this is overcome "by the sense of unity and immersion that career-based storytelling gives," and concluded that "behind the seemingly glamorous work, the silhouette of Lee Ji-eun, a human being who overcame the confusion of the past and proved herself, bloomed more beautifully than anyone else.
"[42] Rolling Stone India spoke of it as a "grand celebration of all things summer and pop," in which "her artistry has only evolved and bloomed into something greater, more powerful and profound," and appreciated the choice to intervene on the album as a producer.
[11] Instead, The Chicago Maroon praised IU's lyrical talent and found Lilac "an album about surveying the rubble of your twenties and picking at shards of memory, not just the glimmering fragments of your best past selves, but also the singed photographs of exes and old friends.
[50] "Lilac" was included in the lists of the best K-pop songs of 2021 compiled by Rolling Stone Korea,[51] NME,[17][52] Billboard[53] and Teen Vogue.