Not yet a week formed, X1 has started promoting their debut. Through their social media accounts, they upload teaser images with the X1 logo and the words "X1 Debut" and "coming soon". There are also 2 boxes containing question marks.
Han, Kim Woo Seok, Song Hyeong Jun, Cho Seung Youn, Son Dong Pyo, Lee Han Gyul, Nam Do Hyon, Cha Jun Ho, Kang Min Hee, and Lee Eun Sang.