Kamui Katsuragi, a central figure in both the original Cardfight!! Vanguard series and its sequel G, first appears as an exceptionally skilled elementary school cardfighter. He possesses a loud, energetic, and often arrogant personality, constantly boasting about his abilities. This confidence partly stems from his dislike of being underestimated due to his young age and short stature, though his talent is genuine. He actively seeks strong opponents while dismissing those he considers weak. His actions are frequently driven by an intense crush on Emi Sendou, younger sister of protagonist Aichi Sendou, leading him to call Aichi "older brother" in hopes of winning Emi's favor. He is nearly always accompanied by close friends Reiji Uno and Eiji Saga; Reiji makes comments that Eiji then abbreviates, ending his sentences with "-ssu!" or "yo!". Past bullying due to his size ended when Gouki Daimonji mentored him, teaching that strength extends beyond the physical. This guidance led Kamui to discover and commit to the Nova Grappler clan, solidified by a promise to Gouki. He frequented Gouki's shop but later joined Card Capital's Team Quadrifoglio (Team Q4) alongside Aichi Sendou, Misaki Tokura, and Toshiki Kai to test his skills against diverse opponents. Within Team Q4, Kamui frequently clashes with Kai for the title of strongest raw fighter, contrasting Kai's detached demeanor with his own passionate and impulsive style. He exclusively uses Nova Grappler decks, favoring a straightforward brute force strategy that leverages the clan's ability to stand rear-guards for multiple attacks per turn. His deck evolves significantly, utilizing various Nova Grappler archetypes: starting with Asura Kaiser and Mr. Invincible, shifting to the Blau series, Beast Deities (featuring Azure Dragon and later Ultra Beast Deity, Illuminal Dragon), the Raizer series (including Perfect Raizer), and later incorporating Legion mechanics with Ultimate Raizer Mega-flare and Dual-flare. In G, he adopts the "Extreme Battler" archetype with Exxtreme Battler, Victor, and later Meteokaiser units, occasionally reverting to updated Beast Deity builds. His core aggressive playstyle remains consistent, and he never wavers from Nova Grappler. Kamui experiences substantial character growth. Early impulsiveness causes conflict, notably leading him to temporarily abandon Team Q4 during a national tournament due to frustration with Kai; he later regrets this and strives to become more reliable. During the Link Joker arc, he is reversed but freed after a cardfight with Aichi, reinforcing the theme of bonds providing strength. A subsequent memory loss arc, where he forgets everything related to Aichi, culminates in a pivotal cardfight against Naoki Ishida; activating Legion triggers his memories' return. He later defeats Kai in a meaningful match, demonstrating the importance of relying on teammates rather than fighting alone – a lesson he imparts to Kai. In Cardfight!! Vanguard G, Kamui attends Hitsue High School and works part-time at Card Capital 2, though his tendency to leave his post frustrates manager Shin Nitta. He mentors new protagonist Chrono Shindou, introducing him to Vanguard and taking a keen interest in his development, partly due to Chrono's unique Gear Chronicle deck. Recognizing Chrono's need for a team to compete at nationals, Kamui forms Team TRY3, strategically provoking Chrono, Shion Kiba, and Tokoha Anjou into setting aside differences to work together. His recognizability as a cardfighter increases significantly. He possesses a distinct, fourth-wall-breaking ability, literally tearing apart Chrono's narration as if it were physical paper. Kamui also habitually misuses words and phrases, confusing similar-sounding terms, which embarrasses him when corrected. His preferred starting turn is second, valuing the first attack opportunity it provides.