On June 9, Mnet's 'Girls Planet 999' confirmed that former Wonder Girls member Sunmi and Girls' Generation's Tiffany will be acting as mentors on the upcoming K-Pop idol survival program. 

Earlier on this day, 'Girls Planet 999' revealed a new teaser clip featuring the program's official 'Planet Master', MC Yeo Jin Goo. While talking about why he chose to participate in 'Girls Planet 999', Yeo Jin Goo also discussed his first meeting with the two K-Pop mentors, two idols who "paved the way for K-Pop". 

Now, Mnet has confirmed that Yeo Jin Goo will be working with none other than Sunmi and Tiffany on 'Girls Planet 999' set to premiere later this summer in August. The newest idol survival series by Mnet, 'Girls Planet 999' tells the stories of 99 female idol trainees from Korea, Japan, and China as they compete to debut in a global girl group.