Koji Fujibayashi

Koji Fujibayashi (藤林耕史 Fujibayashi Koji) is a main character of 48 Days. His epithet is "Bullettrain". Koji's speciality is Riding Duels, with his riding skills being comparable even to those of professional riders.

First concept
Koji runs a Sonic Fusion Deck, which makes high-speed plays during the opponent's turn. His Main Deck monsters are based on the fastest animals in the world, while his Extra Deck monsters are based on the fastest machines.

Edit: His Main Deck monsters are WIND Beast-Type "Supersonic" monsters, while his Extra Deck monsters are WIND Machine-Type "Hypersonic" monsters. His Synchro Monsters let a Fusion Monster be treated as a tuner for their Summon (making the Fusions be right away tuners would spoil it from the beginning).