Eiji Kisaragi's own fighting style makes him a deadly rival of the Kyokugenryu family. Entering the KOF tournament in AOF2, he tried to fight the Sakazakis and was soundly defeated. It was also hinted he used to be with Mai Shiranui before she met and went for Andy Bogard, although it's not comfirmed if they actually had a relationsip or if he was the only one interested. Eiji can be seen surfing on a fish in the start of Mai's Fatal Fury Special stage.

Eiji returns to action in KOF 95 taking part of the Rival team, where he is the rival of the Sakazakis once again, and his teammates (Billy Kane and Iori Yagami) had their own rivals themselves (the Bogards and Kyo Kusanagi, respectively). At the end of the tournament, Iori suffered the effects of the Riot of Blood and all but killed Billy and Eiji. From here on, Billy continued to enter the tournaments following Geese Howard's orders, but mostly for revenge against Iori, though Eiji was never seen again, save a few cameos. Most KOF games have Eiji hop in alongside Billy to throw some threats at Iori whenever Billy and Iori would face off.

Even though Eiji is nowhere to be seen in Art of Fighting 3, the character Jin Fuha enters the tournament looking for him. Due to the time the games were made, perhaps Eiji was still recovering from his beating at the hands of Iori.

Eiji was MIA until the recent KOF XI decided to bring him back in a weird team where he is sided with Kasumi Todoh (another rival of Kyokugenryu Karate, but not to the violent extent that Eiji holds), and Malin, the newcomer from the previous KOF game.

It's curious what role Eiji will play in this game, and if he will have any relation to the Flying Brigade clan of ninjas, either as a new member or a rival. Eiji has always been on his own. Even though he was a villian in AOF2, there was no indication he was ever a member of Mr. Big's sindicate.

His attacks are mostly speed based as well as using energy attacks taking the form of various blades and swords. Eiji is a deadly force indeed.