Gai has tan skin. He has clothing consisting of a yellow full sleeve shirt that he folds up the sleeves to his elbow point and wears a lack jeans. He wears a green sleeveless jumper with frills at the end of the sleeves and down the bottom where the jumper ends. Gai wears dark brown boots that's a little above his ankle and a light brown belt. He also wears a necklace around his neck which happens to have a silver rectangle. Gai has long navy hair which he ties down in a low ponytail with a sky blue ribbon. His low ponytail comes out in front and the same color eyes as his ribbon on his hair. And even though he's the younger brother of Yuri Usui he taller than her, in fact he's the tallest member of Team Ceaser.
He is known as Team Caesar's "Gladiator." Gai styles himself as Koutei's bodyguard, and so takes the field ahead of his teammates. His favored Vanguard is Super Dimensional Robo, Daiyusha, and like Koutei he works to reinforce his Vanguard with supporting units before striking out. However, Yuri often chides Gai for not having a clear winning image which has caused him to lose several key cardfights.