"Blue Valentine" is a song recorded by South Korean girl group Nmixx for their debut studio album of the same name. It was released as the album's lead single by JYP Entertainment and Republic Records on October 13, 2025. The song garnered ten wins on South Korean music programs and topped the Circle Digital Chart.
On September 15, 2025, it was announced that Nmixx would be releasing their first studio album titled Blue Valentine on October 13. On September 24, upon the reveal of the album tracklist, "Blue Valentine" was confirmed to be the album's lead single. Previews of the song were released through the a cappella and original highlight medley videos on October 8 and 10 respectively. On October 12, the music video teaser for the song was released . The song was released alongside its music video on October 13, upon the release of the studio album. The Mixx version was released on October 17, which includes the English and a cappella versions of the song.
"Blue Valentine" was written by J14 (Full8loom), Youra (Full8loom), Danke, Kook Ji-won (Jamfactory), Moon Seol-li, Jellybean (153/Joombas), Milena, and Seora, and composed by Kass, Sevn Dayz, and Stalking Gia. The song is described as "a blend of melancholy synth sounds, guitar riffs and boom bap rhythms at different speeds", showcasing the group's signature, trendy take on the "Mixxpop" genre that fuses more than two musical styles into a single track. It has also been described as a pop rock song.
Nmixx performed "Blue Valentine" on four music programs in the first week of promotion: Mnet's M Countdown on October 16, KBS's Music Bank on October 17, MBC's Show! Music Core on October 18, and SBS's Inkigayo on October 19. In the second week of promotion, they performed on five music programs: MBC M's Show Champion on October 22, M Countdown on October 23, Music Bank on October 24, Show! Music Core on October 25, and Inkigayo on October 26, where they won first place in all appearances.
Credits adapted from Melon.
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