Chang is one of the recurring members of the Korean Team in The King of Fighters series. In Korean, Koehan means giant man, although the more common and generic term for a giant is Guh-in (Korean: 거인). He is one of the many characters in the series to fight with a weapon, a ball and chain.

He was once a feared and violent criminal in Korea. He was spotted by Kim Kaphwan from a prison's surveillance footage and he wanted to use Chang's strength "for justice". Though Chang easily broke out of prison, he was caught by Kim and forced to undergo Kim's "Rehabilitation project" in KOF. During this time, he befriends a fellow convict who was also caught by Kim, Choi Bounge. Together, they initially schemed for ways of escape but they eventually mellow out and enjoy their companions' company — with protests saying otherwise.

Because both him and Choi convinced Kim to join the Garou Team in The King of Fighters XI, they appear in the Garou Team's ending celebrating with them at the PaoPao Cafe. Since they have been deemed "rehabilitated" by their original master, Chang and his smaller companion realize that Kim is on the look out for more villains to reshape and worry for the new victims' future.

(Source: SNK Wiki)