On October 1, 2023, it was announced that Ryokuoushoku Shakai would be releasing "Be a Flower" as the theme song for the Nippon TV anime series The Apothecary Diaries, set to start broadcasting on October 22.[4] They then announced that it would be released as a single on December 6, with advance distribution starting on October 29. The first press limited edition includes a Blu-ray with footage from their Pink Blue album tour 2023 as well as a photobook with images from the tour, and the limited edition includes a Blu-ray with the non-credit opening video of The Apothecary Diaries as well as a digipak with original illustrations from the anime.[5][6] The music video was released on November 15.[7]
The B-side "Dream, Devil & Fantasy"[8] was released to commemorate the 30th anniversary of ZIP-FM [ja], and was aired there from October 31 to December 5.[9]
"Be a Flower" was composed by Shingo Anami, who first created the last piano phrase on the guitar and then wrote the melody. The clap at the beginning of the song was inspired by the manga of The Apothecary Diaries, which had a "continental Asia feeling".[10] Production of the song began in early 2023, with recording in January when the band's album Pink Blue was being produced.[11] Anami and Keita Kawaguchi co-arranged the song. Originally, Anami made a "thick rock sound", but Kawaguchi added traditional Chinese sounds like the erhu and gong. The team for the anime suggested self-love as a theme for the lyrics, and Nagaya wrote the lyrics with this theme by connecting it to Maomao, the protagonist of The Apothecary Diaries, whom she described as the opposite of a typical protagonist.[10]
"Dream, Devil & Fantasy" evolved from a melody that Peppe and Shingo Anami had created in 2021 and was inspired by musical songs. Before writing the lyrics, Issei Kobayashi wrote a short story about "a young man who forgot his dreams", and the lyrics were adapted from the short story.[3] Initially, the song ended with Nagaya singing, but the arranger Lastorder extended it to 30 seconds, and the song ended with piano.[12]
^「花になって – Be a flower」SNSシェアキャンペーン実施決定! ["Hana ni Natte – Be a Flower" SNS Share Campaign Implementation Confirmed!]. Ryokuoushoku Shakai (in Japanese). October 29, 2023. Retrieved December 30, 2023.
^ abAmano, Fumiaki (November 15, 2023). 緑黄色社会「花になって」インタビュー | アニメ「薬屋のひとりごと」OP曲で描く"毒"と"自己愛" (2/3) [Ryokuoushoku Shakai "Hana ni Natte" Interview | "Poison" and "Self-Love" Depicted in the OP Song of the Anime "Yakuya no Hitorigoto" (2/3)]. Music Natalie (in Japanese). Retrieved December 30, 2023.
^緑黄色社会、新曲「花になって」がTVアニメ"薬屋のひとりごと"OPテーマに決定。同曲の一部使用した最新PV公開 [Ryokuoushoku Shakai's new song "Hana ni Natte" has been selected as the opening theme for the TV anime "Yakuya no Hitorigoto". Latest PV released using part of the same song]. Skream!. October 1, 2023. Retrieved December 30, 2023.
^緑黄色社会、TVアニメ『薬屋のひとりごと』OP曲「花になって」シングルリリース+先行配信決定 [Ryokuoushoku Shakai, TV anime Yakuya no Hitorigoto opening song "Hana ni Natte" single release + advance distribution decided]. Barks (in Japanese). October 22, 2023. Retrieved December 30, 2023.
^緑黄色社会「薬屋のひとりごと」OP曲を発売、初回盤に全国ツアーのドキュメンタリー&フォトブック付属 [The opening song of Ryokuoushoku Shakai's "Yakuya no Hitorigoto" is released, and the first edition comes with a documentary and photo book of the national tour]. Music Natalie (in Japanese). October 22, 2023. Retrieved December 30, 2023.
^緑黄色社会、TVアニメ"薬屋のひとりごと"OPテーマ「花になって」MV公開 [Ryokuoushoku Shakai releases MV for TV anime "Yakuya no Hitorigoto" OP theme "Hana ni Natte"]. Skream!. November 15, 2023. Retrieved December 30, 2023.
^ZIP―FM30周年記念ソング第2弾は「緑黄色社会」が担当。9日には「緑黄色社会DAY」を編成 [The second part of ZIP-FM's 30th anniversary song will be performed by Ryokuoushoku Shakai. "Ryokuoushoku Shakai Day" will be organized on the 9th.]. Chunichi Sports (in Japanese). November 1, 2023. Retrieved December 30, 2023.
^ abUeda, Takuto (October 29, 2023). <インタビュー>バンド史上最高難易度、危ういスリルと中毒性――緑黄色社会のアニメ『薬屋のひとりごと』OPテーマは新たな攻めの一曲に【MONTHLY FEATURE】 [<Interview> The highest difficulty in the band's history, dangerous thrills and addictiveness — the opening theme for the Ryokuoushoku Shakai anime "Yakuya no Hitorigoto" is a new aggressive song [Monthly Feature]]. Billboard Japan (in Japanese). Retrieved December 30, 2023.
^Furukawa, Susumu (November 30, 2023). 緑黄色社会 快作『pink blue』を越えてどこへ行く?史上初2on2インタビューで解く! [Where will Ryokuoushoku Shakai go beyond the masterpiece Pink blue? Explained in the first ever 2on2 interview!]. Rockin'On Japan (in Japanese). Vol. 38, no. 1. p. 126. ASINB00GR6GTIS.
^Amano, Fumiaki (November 15, 2023). 緑黄色社会「花になって」インタビュー | アニメ「薬屋のひとりごと」OP曲で描く"毒"と"自己愛" (3/3) [Ryokuoushoku Shakai "Hana ni Natte" Interview | "Poison" and "Self-Love" Depicted in the OP Song of the Anime "Yakuya no Hitorigoto" (3/3)]. Music Natalie (in Japanese). Retrieved December 30, 2023.