It was released as a single on April 12, 2023, by Sony Music Entertainment Japan, serving as the opening theme to the first season of the 2023 Japanese anime series Oshi no Ko.

The lyrics delineate multiple different perspectives on the anime's central character, the idol Ai Hoshino, namely those of her fans, her fellow groupmates, and her own self.

Naoya Nakayama directed the animated music video for the song, which premiered on April 13, 2023, and exceeded 100 million views in around one month, the fastest among Japanese acts.

After numerous domestic and overseas performances, the first Japanese televised performance of the song took place at the 74th NHK Kōhaku Uta Gassen, featuring selected members of Japanese and Korean idol groups,[B] singer Ano, actress Kanna Hashimoto, Real Akiba Boyz, and dance group Avantgardey, which was considered to be the most attracted show of the event.

[1] During a livestream on its official YouTube channel on February 19, 2023, the anime series revealed the opening theme which would be performed by Yoasobi, titled "Idol".

[4] However, the plan was changed after the duo received the offer to perform the opening theme for Oshi no Ko; Ayase interwove the demo and the new composition to be the final version.

[7] A month later, the duo teased a snippet of the English version as a video clip, showing Ikura recording the song in the studio, uploaded via Twitter;[8] the full-length was issued digitally on May 26.

[9] The limited CD and 7-inch vinyl of the single were released on June 21 and July 26, respectively; both formats contains the Japanese, English, anime edit, and instrumental versions.

The title refers to the initials of the manga's fictional idol girl group B-Komachi founding members: Takamine, Nino, Ai, and Watanabe, when typing on a telephone keypad.

[15] The story was first published via Weekly Young Jump's website on April 13, shortly after the anime's first episode televised premiere,[16] before being included as a poster booklet on the single physical releases.

[15] "Idol" combines pop, hip-hop, rock, and video game music genres[17] with a church choir-like gothic rendition.

[18] The Japan Times's Patrick St. Michel described the song as "a mix of varied influences that draws from Akihabara livehouses and Atlanta hip-hop," that is "connected by a piano dash that has come to define Ayase's production.

[22][23] The song's production was inspired by American musician Ghostemane's strong lows and bass guitar played at Indonesia rapper Rich Brian's performance at the 2022 Head in the Clouds Festival.

[24] Music critic Hwang Sun-up noted that "Idol" "reflects a lot of K-pop elements" in terms of sound and composition, citing Blackpink's "How You Like That" for grand intro, and Nmixx's "O.O" for mixed structure.

[25] Ikura's vocals in the song are described as alternating between "cutest idol in the world"-like "sweet and clear" voice and "frenzy" and "introspection" with "deep sarcastic" snarls and "K-pop-esque" "rapid-fire" raps.

Danny Guan from Game Rant praises "Idol" as a "perfect" representation of Ai Hoshino, and "jumping from brooding rap verses to energetic J-pop melodies with ease, flipping moods at the drop of a hat.

"[31] Noriko Ashizawa from Spotify Japan described that "Idol" "has a composition in which the scene changes rapidly in a different sense from K-pop," and "the Vocaloid-like irregular melody progression is not similar to any overseas song.

[D][E] The Recording Industry Association of Japan (RIAJ) certified "Idol" double platinum for digital sales, exceeding 500,000 units,[53] and diamond for on-demand streaming with 500 million times.

[55] Japanese Society for Rights of Authors, Composers and Publishers (JASRAC) reported that "Idol" was the highest earned royalties in Japan in 2023.

[56] For the issue dated April 24, 2023, "Idol" entered the Oricon Digital Singles Chart at number two, earning 33,867 downloads, behind Man with a Mission and Milet's "Kizuna no Kiseki",[57] and rose to the top the next week with 34,070 downloads, making it as Yoasobi's record for the most number-one song on the chart with 12 songs, tying with Kenshi Yonezu at that time.

It earned 29,327 digital sales, 8,868,810 streams, and 4,334,923 video views in its first week, scoring Yoasobi's second number-one song in the country since "Yoru ni Kakeru" in 2020.

[75][76] In the week of September 13, the song was finally unseated in the top position by Snow Man's "Dangerholic", King Gnu's "Specialz", and Enhypen's "Bite Me", descending to number four.

[112] The International Federation of the Phonographic Industry (IFPI) reported that "Idol" was the nineteenth best-selling song in 2023, earning 1.01 billion subscription streams equivalents globally.

[115] In the end, it shows Aqua and Ruby as high school students watching her mother Ai performing on television, which does not appear in the anime.

[135] Choreographed and staged by Ganmi's Sota Kawashima,[136] "Idol" was presented as the 42nd show (excluding special performances), preceded by Fumiya Fujii's "True Love" and "Shiroi Kumo no Yō ni" with Hiroiki Ariyoshi, and succeeded by Masaharu Fukuyama's "Hello" and "Sōbō" medley.

Following the first verse, selected members from that year's ten participating Japanese and Korean idol groups—Seventeen (Hoshi, DK, Mingyu, and Seungkwan), Nogizaka46 (Minami Umezawa, Renka Iwamoto, Mizuki Yamashita, Haruka Kaki, Mayu Tamura, and Nao Yumiki), NiziU (Mako, Riku, Ayaka, Mayuka, and Miihi), Be:First (Sota, Leo, Junon, and Manato), NewJeans (Minji, Hanni, and Danielle), JO1 (Shosei Ohira, Syoya Kimata, Sukai Kinjo, Junki Kono, and Ruki Shiroiwa), Stray Kids (Felix, Seungmin, and I.N), Sakurazaka46 (Yui Kobayashi, Rina Matsuda, Yui Takemoto, Hikaru Morita, and Rena Moriya), Le Sserafim (Sakura, Kim Chaewon, Huh Yunjin, and Kazuha), and MiSaMo—performed one after another.

from DVL, respectively—who both gained attention from fan-taken photos comparison of the two during idol career, nicknamed "the final battle between angel and devil", appeared and did their viral posture.

[140] Despite the lowest rating (31.9% audience share) since 1989,[141] Yoasobi's "Idol" show was considered to be the "highlight" and "the most attracted attention" of the event, especially online.

[156][157] Other notable covers included Yuya Tegoshi,[158] Ayaka Hirahara and Avantgardey,[159] Aya Shimazu,[160] Toshi,[161] Junretsu,[162] La Diva (Ryoko Moriyama, Ayaka Hirahara, Seiko Niizuma, and Sarah Àlainn),[163] and NiziU, Me:I, Fruits Zipper, Candy Tune, Sweet Steady and Cutie Street, etc.

[165] In late April 2023, Shortly after "Idol" release, a recreated video of the title sequence of Oshi no Ko connecting to the title sequence of Shin Getter Robo vs Neo Getter Robo, in which "Idol" was changed in the middle of the chorus to JAM Project's "Storm", "Kimi wa kanpeki de kyūkyoku no Gettā",[J] went viral and became an Internet meme, which both Yoasobi and JAM Project former member Ichirou Mizuki's official Twitter accounts each responded the video.