Saturday (세러데이) is a six-member girl group under SD Entertainment. They debuted on July 18, 2018 with the single "MMook JJi BBa". On July 5, SD Entertainment reveal that a new girl group will debut the same month. Their name will be Saturday and the group will be consisting of seven members. On July 7, the first member of the group Yuki was revealed, followed by Ayeon on July 8, Chohee on July 9 and Haneul, Chaewon, Sunha, Sion on July 10.

On July 10 the first teaser for the group's debut single "MMook JJi BBa" was released and the second one on July 15. The group officially debuted with the music video for "MMook JJi BBa" on July 18, alongside the M/V they released introduction videos in: Chinese, English , Korean and Japanese. - Kpop.Wikia