Kim Jae Seop, later legally changed to Kim Si Yun and formerly known professionally as AJ, is a South Korean singer, dancer, actor, composer and former member of PARAN (파란) and U-KISS (유키스). He graduated from Columbia University with a bachelor's degree in Psychology.

He made his debut in August 2005 as PARAN's vocalist with their first single album, "Paran The First". The group was managed by Global H Media (글로벌에이치미디어, formerly known as NH Media) and was targeted for the international market as all member were fluent in English and Japanese and had experience in all areas of musical production from chorus, dubbing to sub-producing. However, they were never able to find success as some members enlisted in the military and others decided to pursue individual activities. They never officially disbanded, but have not released any material since 2008.

He re-debuted in March 2011 when he joined as U-KISS's main rapper and vocalist with their fifth EP, "Bran New Kiss". The group had debuted in 2008 but, the agency decided to add him to the lineup to replace departing members Alexander and Ki Bum.

Later in 2011, they debuted in Japan with the single "Tick Tack" but soon after, he was admitted to Columbia University and went on hiatus to continue his education. He performed with the group when his schedule allowed it and, in August 2016, he announced his departure from the group as his contract expired.

He joined Rooftop Company (루프탑컴퍼니) and debuted as a solo artist in July 2017 (using his legal name) with the mini-album "Surreal, But Nice".

In mid-2023, he returned to the group for their 15th anniversary reunion and held concerts in Japan and in South Korea.
As he remains under contract with Rooftop, he joins U-KISS activities occasionally but is open to an eventual return to the group.

(Source: MyDramaList) Edit Biography