In The King of Fighters, Kyo is a descendant of the legendary Kusanagi clan, and inherits from his family pyrokinetic powers, the ancient Kusanagi martial arts style, and an ancient enemy to both the Orochi and his minions, as well as Iori Yagami, last descendant of the treacherous Yasakani clan.
In The King of Fighters '95, the story about Kyo's clan was revealed: the Kusanagi and Yasakani clans were once allies, uniting along with the Yata (later known as Kagura) clan to seal away the evil Orochi 1800 years ago. However, the Yasakani clan, out of jealousy over the fame of the Kusanagi, eventually struck an unholy and treacherous pact with Orochi, and became the Yagami. Since then, the Kusanagi clan has been forced to use the crimson flames that put Orochi to sleep against their former allies. Many members of both clans have perished in this rivalry, up until the events of the King of Fighters games, in which Kyo and Iori must end a battle spanning 660 years.