Kayaba Akihiko (茅場晶彦, Kayaba Akihiko?) was the development director and GM (Game Master) of «Sword Art Online». He was also the designer of the «NerveGear», the Cardinal System, and «The Seed», as well as the main antagonist of the Aincrad Arc. He played SAO as the leader of the «Knights of the Blood», Heathcliff (ヒースクリフ, Hīsukurifu?).