The group consisted of five members: Jo Yong-geun, Kim Hyun-soo, Jung Yoo-jun, Park Woo-dam, and Woo Jin-young.

[2] Park Woo-dam, Woo Jin-young, Jo Yong-geun participated in the Mnet survival series Produce 101 Season 2 in 2017 under Happy Face sub-label HF Music Company.

[3][4] Park Woo-dam, Woo Jin-young, Jo Yong-geun, Kim Hyun-soo and other Happy Face trainees participated in the JTBC survival series Mix Nine in September 2017.

All the members was previously introduced as a pre-debut team HNB (HappyFace Next Boys) and had released several songs as unit or duo since 2017.

In March 2019, Happy Face Entertainment confirmed the five members to debut in the group and set up their own-group label.