Aichi Sendou

Aichi Sendou is the main protagonist of the Cardfight Vanguard anime and manga. He is a somewhat shy and timid young man who wishes to be a Vanguard Fighter but has never had the chance to have a real fight until his second encounter with Kai. When starting to play Vanguard he believes more in himself becoming a powerful Vanguard Fighter. His Vanguard Circles color is blue but when using a Shadow Paladin deck the color changes to dark blue. Source: Cardfight Vanguard Wiki