Wonder About Us! Hello, I'm Jinsung! Jung Jin Sung (정진성) is a South Korean singer and dancer under Play M Entertainment. He is a member of project group 1THE9, as well as trainee group PlayM BOYS.
On October 25, 2018, Jung Jin Sung was introduced as a contestant of Under Nineteen with his moving poster. The poster revealed that he was a part of the vocal team. He finished in second place, thus becoming a member of the project group 1THE9.