On October 10, MBC revealed, "Power vocalist Solji will be joining 'Under Nineteen' as a vocal director." Solji also added, "I'm so happy to be able to participate in 'Under Nineteen' as a vocal director. I feel joyful at the fact that I can help young friends who are just taking their first steps. I also want to work together with the other directors to create great teams. Please look forward to it, since there are many friends with bright futures."

'Under Nineteen' is an audition program aimed towards teenagers. Individuals who prove themselves in the categories of vocal, rap, and performance will be grouped together to form a unique new idol group. Other vocal directors currently confirmed include Crush, Dynamic Duo, and Super Junior's Eunhyuk. 

Meanwhile, 'Under Nineteen' premieres in the first week of November!