Just B (Korean: 저스트비) is a South Korean boy band formed by Bluedot Entertainment. The group consists of six members: Geonu, Bain, Lim Ji-min, JM, DY, and Sangwoo.

Under Nineteen (Korean: 언더나인틴) was a survival show on Munhwa Broadcasting Corporation for trainees under the age of 19 years old. There were a total of 57 contestants competing to debut as a member of 1THE9. The trainees were put into groups that specializes in vocals, rapping, and performance. The show aired between November 3, 2018 and February 9, 2019.