Fromis 9 (Hangul: 프로미스나인 or 프로미스 9; initialism for From Idol School; stylized as fromis_9) is a South Korean girl group formed by CJ E&M through the 2017 reality show Idol School. The group's name, pronounced as "promise" in Korean, also means "to keep their promise [to viewers] to be the best girl group". The group composed of nine members: Roh Ji-sun, Song Ha-young, Lee Sae-rom, Lee Chae-young, Lee Na-gyung, Park Ji-won, Lee Seo-yeon, Baek Ji-heon and Jang Gyu-ri. The group officially debuted on January 24, 2018 under Stone Music Entertainment with the release of their first extended play (EP), To. Heart.