Olivier Gaillard

"Olivier Gaillard" is one of the main antagonists of Season 4 and one of the four members of the Quatre Knights. He is also the European Circuit Champion and provided assistance with the eradication of Link Joker. The color of his Vanguard Circle is dark blue. Olivier claims that he inherited Aichi's will; Olivier also states that he will do anything to prevent anyone from disturbing Aichi.

(Source: Cardfight!! Vanguard Wiki)