On September 8 KST, BOYS24 revealed an unexpected, mysterious spoiler through their Twitter account.
There are four total pictures, and they all appear to be hand-drawn by one of the members, as the last drawing says By JYT, most likely standing for Jeong Yeontae.
#090909#1st #SPOILER pic.twitter.com/EoNgTjyuw6
소년24_BOYS24 (@Boys24_official) September 8, 2017
BOYS24 confirmed their final members for debut last month. They are, Hwang Inho, Jeong Yeontae, Kim Jinsub, Kim Sunghyun, Yoo Youngdoo, Issac, Lee Inpyo, and Han Hyunuk. While Jin Sungho made it into the final nine, he announced his mutually-decided leave from the group, and addressed his fans with a personal letter.