MustB was a five-member boy group signed under MUSTM Entertainment, the label's first K-pop group. This group consists of: Doha, Taegeon, Wooyeon, Soohyun, and Sihoo. They debuted with the track, "I Want U", on the 1st of December 2018.

On April 21, 2019 MustB was involved in a car accident. Following the car accident Hawoon and Sangwoo both left the group. Read more on Last.fm. User-contributed text is available under the Creative Commons By-SA License; additional terms may apply.