Kyohei Kadota attended Raijin Academy alongside Izaya Orihara, Shizuo Heiwajima, and Shinra Kishitani. During this time, he frequently stepped between Shizuo and Izaya to mediate their violent conflicts and prevent widespread destruction. Izaya gave him the nickname "Dotachin," which Kadota disliked but his friends adopted anyway. Rumors of his formidable fighting ability earned him the moniker of Raijin High School's "Shadow Boss," though he never pursued leadership in any gang or territory.

He later joined the Blue Squares gang with his close friends Saburo Togusa, Erika Karisawa, and Walker Yumasaki. However, he betrayed the Blue Squares during a conflict with the Yellow Scarves, disgusted by their leader's brutal methods. Kadota and his friends rescued Saki Mikajima, delivering her to safety at a hospital and renouncing their gang ties. This act revealed his refusal to compromise his principles, even against powerful groups. Months later, he accepted an anonymous invitation to join the Dollars, seeing it as a practical alternative to traditional gangs. Though suspecting Izaya as the founder, Kadota became an active and respected member. His leadership within his tight-knit friend group solidified, often using their van as a base.

Kadota maintains a calm, perceptive, and serious demeanor, guided by a strong sense of justice. His significant hand-to-hand combat skills were honed through numerous street fights. He readily assists others, demonstrated when saving Anri Sonohara from a Saika-wielding attacker and investigating Yagiri Pharmaceuticals' connection to disappearances. His charisma grants him influence, enabling him to call in favors from a broad network beyond his immediate circle. Physically tall with dark hair and brown eyes, he typically wears a teal collared jacket, jeans, sneakers, and a distinctive black beanie.

During the Toramaru conflict, Chikage Rokujou confronted Kadota at Raira Academy, mistakenly believing him to be the Dollars' leader due to his reputation. After a brutal fight where both sustained heavy injuries, Kadota emerged slightly victorious. He then negotiated Toramaru's withdrawal from Ikebukuro, promising to identify and hold accountable the rogue Dollars members who had attacked Toramaru's non-combatant associates. He emphasized this action stemmed solely from his personal ethics, not as a Dollars representative, stating his hatred for involving innocents in gang conflicts.

When rogue Dollars members ambushed the injured Kadota and Chikage, taking Chikage's girlfriend Non and her friends hostage, Kadota's core group and allied Dollars members intervened. They secured the hostages' safety, sparking a chaotic battle between the allied Dollars-Toramaru forces and the rogue elements, ultimately interrupted by Shizuo Heiwajima. This event reinforced Kadota's commitment to opposing anyone, even fellow Dollars, who targeted civilians.

His relationships define him. He shares unwavering loyalty with Saburo, Erika, and Walker, forming an inseparable group almost always together. Despite their eccentricities and tendency to involve him in chaos, he deeply values their camaraderie. His history with Izaya and Shizuo is complex; he remains one of the few individuals Izaya treats with some respect and one of the fewer still Shizuo tolerates without violence, a testament to his mediating role during their school years.