Kenji has short blonde hair, and silver eyes. Wears white pants, dark shoes and a long, crimson red coat. Around his neck he wears a small pendant originally given to him by Yuri.
Kenji is a friendly and courteous man. He is friendly to most people and is in a good mood most of the time. He always tries to be gentle with people, and has no bad intentions with anyone. Although it has been shown that he can be a little confused from time to time. He especially does not take losses hard and sees them as an opportunity to learn and grow, especially if they are willing to give advice like Yuri and Kai.
Although Q4 is a rival to Team Caesar in the 1st and 2nd Cardfight!! Vanguard Nationals Tournaments, he and his team maintain a friendly relationship with them, wishing them "good luck" when they are found.
This all changes after he is Reversed. Kenji, whose desired a way to uphold his "justice" against his strong opponents, was given the power to upgrade his deck with the power of Reverse, but this came at the cost of his sense of justice, leaving him a tyrant who uses the word to bend his followers to his will, while destroying anything that opposes him, similar to Leon's Justice in season two. Ironically, it was Leon who defeated him and returned him to the normal friendly Emperor he desires to be.
The national champion from two years prior to the beginning of the series, and the captain of Team Caesar. Kenji loves Roman history and models himself on Gaius Julius Caesar; it's for this reason that he's called "Koutei," the emperor of Team Caesar.
Before becoming the strong competetor that he is now, Kenji Mitsusada, a young rookie cardfighter, stumbled across Gai and Yuri's card shop and asked for a cardfight. Many times however, he lost due to his inexperience but quickly learned and grew fast as a cardfighter. Eventually Yuri, who was looking for a third cardfighter for their team alongside her brother, allowed him to join their team. Since then Kenji's skills as a cardfighter improved by leaps and bounds, eventually beating Yuri and Gai and took over as leader of their team and inheriting Yuri's metal necklace.
Humbled by Ren's PSYqualia during the first national, Koutei takes note of and arranges to meet with Team Q4. Caesar and Q4 form a powerful bond, working together in preparation for the second half of the tournament season.
Kenji makes his following appearance at the next national, pitted against Aichi Sendou. Ultimately Kenji loses the match, and retires to the sidelines.
In Season 2, Kenji and Team Caesar are invited to participate in the VF Circuit alongside teams such as Team Q4 and Team New Asteroid. After losing in the Singapore stage to Team S.I.T. Genius Kenji is pitted against Ren Suzugamori in the Seoul stage. During the fight Kenji declares Final Turn and superior Crossrides Ultimate Dimensional Robo, Great Daiyusha and defeats Ren. However; the rest of Team Caeser loses thus allowing Team New AL4 to win the Seoul stage. Later on Kenji winds up at Shop Handsome looking for Aichi but ends up fighting and beat Gouki Daimonji. After the fight he announces that he will be attending SIT University and will not be participating in tournaments until he graduates. He is last seen on a plane bound for Singapore while donning the headband he inherited from Gouki after their fight.
In season 3, he has returned from his studies at Singapore. In his first appearance this season, he is on a plane returning to Japan. Gai and Yuri planned to pick him up from the airport, but they were stuck in traffic. When he got off the plane, Kai greets him in the lobby. They cardfight, with Kai as the victor, Kai then Reverses Kenji and Daiyusha. Kenji later meets up with Christopher Lo and cardfights him, winning with Dark Dimensional Robo, "Яeverse" Daiyusha's Limit Break, following this, Yuri, who had run ahead to meet him, ends up fighting him after seeing something wrong with him. Yuri is defeated, and Leon soon enters into battle with the Emperor. Getting an edge by Superior Riding, he manages to activate "Яeverse" Daiyusha's Limit Break twice. However, Leon makes a comeback and wins by using Blue Wave Dragon, Tetra-drive Dragon. They proceed to un-Reverse the others, and he and Yuri later meet up with Gai, who was forgotten.
In season 4, he continues to travel the world increasing his skills. He lost all memories of Team Q4 and thus is not acquainted with Misaki and Kamui. He is also seen with two of the Quatre Knights, Raul Cera and Ratie Curti but does not know of their agenda. Ratie forces him into a Cardfight where she wins using her Shadow Paladin witches. He recieves a call from Yuri but when he returns, he finds Ratie and Misaki disappeared. By the time Yuri and Gai showed up, he had given up finding them and leaves with his team.
Still focusing on the Dimensional Robo series, he now uses the Crossbreak Ride Ultimate Dimensional Robo, Great Daikaiser which allows Koutei to Triple Drive Check. Coupled with Daikaiser's Break Ride ability, he can smash through the toughest defenses and end his opponents in one hit. To help achieve his winning image more easily, Koutei uses several units that allow him to Superior Ride Daikaiser and Great Daikaiser directly from the Deck.