Choi Sang Yeop

Choi Sang Yeop was VIXX Ken's duet partner for the Duet Song Festival in 2016. He then participated in OSTs and made his solo debut on November 14, 2017 with his EP Yeop x 2. Choi Sang Yeop joined JTBC's audition show SuperBand in 2019 but was eliminated on the first round.

After Lee Ju Hyuk's departure from LUCY before the Top 3 Superband Concert, he was contacted to replace him. On March 27, 2020, MYSTIC89 announced they signed with the band and the group debuted on May 8, 2020 with their first single "Dear. ".