K' debuted as the leader of the Hero Team in King of Fighters '99. K' was once a normal child who lived with his sister, Seirah. One day, NESTS (a crime syndicate who deals with drugs, genetics, robotics & biotechnology) kidnapped K' and his sister. Over the yeasr, NESTS trained K' to be some kind of weapon. In 1998, K' was to take part in the Kusanagi cloning program. After K' was infused with Kyo's DNA, he was granted the power of pyrokinesis. K's memory was wiped by NESTS and he was made to believe that he was Krizalid's clone.
NESTS ordered K' and Maxima to join the King of Fighters tournament along with Benimaru and Shingo. The team made it to the finals and were sent to find Krizalid,