Shion Kiba

Shion Kiba is one of the main characters of the Cardfight!! Vanguard G. As the heir to the Kiba family fortune, he was brought up to be a man befitting the upper class. One day, his fencing classmate lost a card, which Shion accidentally destroyed. During a trip to a card shop to buy a replacement, he noticed a Blue Sky Knight, Altmile on sale. This was the catalyst for Shion becoming a cardfighter. His vanguard circle is blue. He is also the former rival of Chrono Shindou.

(Source: Cardfight!! Vanguard Wiki)