PJ

Hyunjin started a YouTube channel during his university years to talk about misunderstandings surrounding people with hearing impairments. He was later casted in the EBS TV show Go Together, where he met model Kim Jong-wook who introduced him to his agency Parastar Entertainment and the "K-pop idol with hearing impairments" project. On August 2, 2023, he was revealed as one of the members for Parastar Entertainment's upcoming boy group Big Ocean, The group debuted on April 20, 2024, with the digital single "Glow".

On April 2, 2025, Hyunjin announced he will be changing his stage name to PJ (which comes from his birth name Park HyunJin). On June 28, Big Ocean announced the subunit Big Ocean JJ consisting of members PJ and Jiseok. The unit made their debut on July 9 with the digital single "Bucket Hat".