Kim Jae-han, formerly known as J.Han, is a South Korean singer, dancer, actor, producer, lyricist, former member of ONEVOICES and SPECTRUM and current member of OMEGA X. He graduated from Seongdo High School.

He made his debut in May 2015 (under the stage name J.Han) as part of the duo ONEVOICES with their first mini-album, "Flush". They were not successful and the agency, HAK Entertainment, decided to disband the duo right after promotions for their debut album ended.

He switched agencies and re-debuted in May 2018 (using his real name) as SPECTRUM's main vocalist with their first EP, "Be Born". Unfortunately, after some initial success, the group could not continue to promote due to the COVID-19 pandemic and their agency, Wynn Entertainment had to cut expenses and decided to disband the group in July 2020.

After switching agencies again, he re-debuted in July 2021 as a member of OMEGA X with their first single album, "Vamos". However, in October 2022, a video of the CEO of OMEGA X's label (Spire Entertainment) abusing him and his group members came to light. The members filed a lawsuit against their company to cancel their exclusive contracts and to file for the trademark of their group name. In January 2023, OMEGA X won the lawsuit and officially ended their contract with the agency. This was finally made official on May 8, 2023. The group is has been represented by IPQ since July 2023.

He has written and produced several songs and he made his acting debut in 2023 with a main role in the BL drama "A Shoulder to Cry On".