Wonder About Us! Hello, I'm Junseo! Kim Jun Seo (김준서; or simply Junseo) is a South Korean singer and rapper under OUI Entertainment. He is a member of the project group 1THE9 and the trainee group OUIBOYS.
On October 25, 2018, Kim Jun Seo was introduced as a contestant of Under Nineteen with his moving poster. The poster revealed that he was a part of the performance team. He finished in ninth place, thus becoming a member of the project group 1THE9.