The stories in The King of Fighters games go far beyond fighting tournaments. The Orochi saga involved power-hungry arms dealers, ancient evils, and warring clans. After that, the NESTS saga with bioengineered clones and a secret organization bent on world domination may seem passe, but it introduced a lot of fan-favorite characters to The King of Fighters. K', Maxima, Vanessa, Kula Diamond, and Whip all stem from the NESTS saga in King of Fighters‘99, 2000, and 2001.
NESTS is a secret organization that deals with criminal activity, corrupt business deals, weapons dealing, and bioengineering. It learned about Orochi power during the previous King of Fighters tournaments, and kidnaps Kyo Kusanagi after the ‘97 tournament. They begin the Kusanagi Cloning Program, which turned children into human weapons based on Kyo’s DNA. A boy eventually known as K’ gains the power of pyrokinesis, and a clone of him named Krizalid had altered memories to believe he was the original. K's memories, including his sister in the program, were also erased or repressed.
The King of Fighters ‘99
The King of Fighters tournament returned in 1999, but with teams of four instead of three - the fourth being a “striker” who could be called help for a limited amount of times. During the tournament, reports of Kyo showing up at multiple locations around the world leads to Heidern, the leader of the Ikari Warriors mercenary team, looking around. The Hero Team, of which K’ and fellow NESTS operative Maxima are a part, wins the tournament and is taken to an underground base to meet Krizalid, who reveals the NESTS organization used the tournament to collect combat data for a clone army.
K’ defeats Krizalid, and NESTS blows up its base. K’ and Maxima manage to escape, and K’ discovers he was a test subject of NESTS before deciding to take them down. Whip, a new operative for the Ikari Warriors, returns to the NESTS base ruins and finds Krizalid, barely alive. She asks if he remembers his father’s face and reveals he is a clone, and that K’ is her brother. He dies and is brought back to the Ikari Warriors mercenaries.
The King of Fighters 2000
Heidern is determined to figure out NESTS’ objective, searching for K’ and Maxima for interrogation. The King of Fighters tournament occurs again and many of the teams return alongside some newcomers. A new fighter named Kula Diamond, created as part of NESTS' new Anti K program, appears to kill K’ under orders from NESTS. However, she fails. The tournament is revealed to have been hosted by Zero, a rogue NESTS member who wishes to destroy the organization and create a new world order.
He utilizes power gathered during the tournament to launch a space-based satellite weapon called the Zero Cannon, and destroys South Town (a well-known city in SNK games where the Fatal Fury games take place and older King of Fighters tournaments were held). K’ and the Hero team defeat him, and Heidern prevents Zero from using the cannon again. Kula and her cohorts Foxy and Diana appear to destroy the cannon, and Whip later kills Zero.
The King of Fighters 2001
Following the destruction of South Town, the public calls for an end to the King of Fighters tournament. However, this also makes the fighting competition more popular than ever. Despite public outcry, NESTS decides to host the latest tournament and enters its own team consisting of Kula, Foxy, Angel, and the 9,999th clone of Kyo: K9999. The Hero team wins again, and they meet Original Zero whose clone was behind the previous year’s tournament. He challenges the Hero team alongside his pet lion, NESTS operative Ron, and a revived Krizalid as find the real NESTS headquarters in a space satellite.
The leader of NESTS, Nests, reveals himself before getting killed by Igniz, who claims ownership of the organization. He reveals that K’, Krizalid, Kula, Whip, and K9999 were created as guinea pigs. Declaring himself a god, he attacks the Hero team as his first act of “divine retribution." Other fighters show up and prevent Igniz from winning, retaliating by plunging the satellite into Earth. However, Ron secretly directs the satellite to lands in the ocean and the fighters all survive, with the only casualty being Igniz. Kula and her cohorts join K’, but K9999 goes missing. Igniz’ death marks the end of the NESTS cartel in King of Fighters.