The first game in the series introduces the initial main character of the series, Kyo Kusanagi, a young Japanese fighter who is the heir to a powerful group of martial artists having pyrokinetic abilities. Kyo fights against the Kusanagi clan's enemies, his rival Iori Yagami, and the snake demon Orochi and its human followers, among others. The first four games in the series revolve about these fights, while The King of Fighters '99 introduces a new story arc, revolving around K′, a young man who seeks to destroy the mysterious NESTS organization because they kidnapped him at an early age and stripped him of his past memories, so that they could force him to be a fighter under their control. In The King of Fighters 2003, a new character named Ash Crimson enters the tournament, to steal the powers of the clans who sealed the Orochi in the past for unknown reasons. A new group of antagonists, known as Those From the Past, also appears in the series; they want to obtain Orochi's power for the purpose of giving it to their unknown master.
