Kim Sang Gyun, formerly known as A-Tom, is a South Korean singer, dancer, former member of TOPP DOGG (탑독), JBJ (제이비제이) and part of the duo JBJ95 (제이비제이구오).

He graduated from Gwangdeok High School and later obtained a bachelor's degree in Broadcasting Entertainment from Global Cyber University. Before debuting, he was a backup dancer for the girl group EVOL (이블).

He made his debut in 2013 (using the stage name A-Tom) as TOPP DOGG's rapper and vocalist with their first EP, "Dogg's Out". The group was not very successful, and the style did not fit all 13 members.

In early 2017, he joined "Produce 101 Season 2" (using his real name), and despite finishing in 26th place, fans chose trainees ranked 20-30 to debut in a project group called JBJ. At the same time, TOPP DOGG was rebranding as XENO-T (제노티), and he decided not to re-join them. Instead, he re-debuted in October 2017 as part of JBJ with their first EP, "Fantasy". The agency then chose not to extend the project, and JBJ disbanded 6 months later.

Soon after, it was revealed that he and Kenta would continue to collaborate and formed the duo JBJ95 under Star Road Entertainment (스타로드엔터테인먼트). They debuted with their EP "Home" and were well received by the public and the media. However, in April 2021, both sued the agency, citing a lack of management and payment and asking for their contracts to be terminated. In October 2022, results came out, and they were granted the termination of their contracts, but they were also found guilty of violating the terms of said contracts and had to pay the corresponding penalties.

The duo now promotes mainly in Japan under the name KENTA・SANGGYUN.

(Source: MyDramaList) Edit Biography