Pronounced "Kay-Four-Nine", a King of Fighters character who is blatantly based on AKIRA's Shima Tetsuo, right down to Sasaki Nozomu voicing him. He was later replaced by Nameless as of Unlimited Match. He also got another redesign (closer to the original concept) for The King of Fighters XV with his moveset named Krohnen. Which happens to actually be K9999 himself.
He is the 9999th clone of Kusanagi Kyou.
He is often depicted along with fellow NESTS member Angel.