CLASS:y (클라씨) is a South Korean girl group formed through the MBC reality competition show My Teenage Girl (TeenageGirls) under M25 and Universal Music Japan. The group consists of seven members: Hyungseo (형서), Chaewon (채원), Hyeju (혜주), Riwon (리원), Jimin (지민), Boeun (보은) and Seonyou (선유). They officially debuted on May 5, 2022, with the extended play (EP) "CLASS IS OVER. On May 26, 2022, CLASS:Y released their second series of their debut extended play, "LIVES ACROSS".