All nine members will be taking part in the creation of the theme song titled "I Believe in this Moment". You can see the girls' dedicated, hard work in progress, as well as a preview of the OST Part 1, which will be released in full this July 17 in conjunction with the first episode of 'School 2017'. 

SEE ALSO: Gugudan to make a comeback as 8 members

Meanwhile, 'School 2017' stars Gugudan's Kim Se Jung, Kim Jung Hyun, Jang Dong Yoon, Sunhwa, SF9's Rowoon, and more.