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.