Ryuji Yamazaki/Story

Past
Yamazaki was orphaned at a young age in the streets of Okinawa. His life was a miserable and boring existence — with American troops constantly patrolling his town — until he caught glimpse of a well-dressed yakuza boss named Sorimachi. Aspiring to be like the man he saw, Yamazaki left his town and joined the crime syndicate. Eventually, he worked under Sorimachi, the man he admired as a surrogate father, and found happiness for the first time in his life as his bodyguard.

Unfortunately, Yamazaki's uneasiness during a fateful business trip to Osaka alongside his boss marked an ambush from a rival gang, and from there his boss Sorimachi was tortured and killed. The shock of his death gave birth to Yamazaki's insane alter ego.

Although he has little memory of his past after this incident, Yamazaki murdered his boss's rival and fled from Japan to Hong Kong. He continues to be an influential broker, weapons dealer, and drug trader with Kowloon Walled City as his base of operations. He is usually at odds with Hon-Fu, who tries to catch and arrest him in the act.

Fatal Fury 3
Ten years later, in 1995, he joined the Chinese mafia and was hired by Jin Chonrei and Jin Chonshu to protect them and the scrolls of immortality. In his Fatal Fury 3 ending, Yamazaki is arrested by local authorities, yet he beats the police officers around him and escapes. He is presumably still on the run from the law.

The King of Fighters
Yamazaki's life in this timeline is exactly the same as his mainline counterpart up until Fatal Fury 3: Road to the Final Victory.

The King of Fighters '97
As he was trashing another dojo, Yamazaki met Billy Kane. On Geese's orders, Billy requested the broker's participation in the tournament. Yamazaki refused at first, but after terribly mauling one of the warriors, he felt an adrenaline rush through his blood. He then accepted Billy's offer and demanded to be paid double the amount of the tournament's prize money. During the tournament it was revealed that Yamazaki is one of the Hakkesshu.

The King of Fighters 2003
He returns in the 2003 tournament with Billy and Gato on another of Geese's schemes. In their team's ending, Billy and Yamazaki engage in a brawl and neither have made an appearance in KOF XI. Whether or not this ending in canon remains to be seen, although it does somewhat explain the characters' disappearance.

The King of Fighters XIV
This section is currently considered non-canon.

During an interaction with Rock Howard, he seemingly knows that he is Terry's protégé, and he's looking for him. In an attempt to lure him out, he attempts to attack Rock. In another interaction, he causes trouble with Vanessa and Whip.