A hidden, recessive program deep within the SPT-LZ-00X Layzner capable of overriding Rei, this AI had the persona of an adult male yet still kept the amorality of its predecessor. Programmed by Ken Asuka as a way of conveying information about Grados to the Earthlings, Fouron would only ever surface when the Layzner was critically damaged or Eiji was in serious danger of dying: its trademark purple eyes marking its complete control over the SPT, even its V-MAX system.