Good Day (Korean: 굿데이) is a ten-member South Korean girl group formed by C9 Entertainment. They debuted on 30th August, 2017, with their 1st mini album “All Day Good Day”.
On 30th August, they debuted with their first mini album “All Day Good Day”, with the music video for their debut title track “Rolly” featuring the appearance of C9 Entertainment trainee and current Wanna One member Bae Jin-young. The other 3 tracks from the mini album are songs from the group’s 3 units: Good Morning, Good Night and Midnight. On 3rd September, they have held their debut mini concert “All Day Good Day” at the Yes24 Live Hall.