Prior to his imprisonment, Bundō Rokuro attended Nagano Middle School, where he was a classmate of Kasuga Kyōko and a student of Idaki Hitara. At an unspecified time, he was incarcerated within Deadman Wonderland, a privately-run prison that housed individuals with special abilities known as Deadmen.

During his time in Deadman Wonderland, Bundō became affiliated with Scar Chain, a resistance faction opposing the prison’s corrupt administration. However, he also served as a double agent, acting as a spy for the Undertakers under the orders of Tsunenaga Tamaki. As part of his mission, Bundō played a key role in fabricating a staged confession video of Ganta Igarashi, falsely implicating him in the Nagano School Massacre.

Bundō Rokuro is a young man with medium-length black hair that falls just above his eyes, with slightly longer strands framing the sides of his face. His complexion is notably pale, and his dark gray eyes lack visible pupils, giving him a distinct and somewhat unsettling appearance.

His attire consists of a black long-sleeved T-shirt with a wide neckline, paired with gray pants. A notable feature of his clothing is the Scar Chain logo, which is prominently displayed on both the left side of his chest and his back, signifying his affiliation with the resistance faction.

Bundō Rokuro exhibits an apathetic and emotionless attitude, particularly during his time as a spy for the Undertakers. His facial expressions remain consistently vacant, giving little indication of his true thoughts or intentions. However, beneath his passive exterior lies a calculating and manipulative mind. He is highly analytical, obsessively fixating on probability and control, which fuels his meticulous decision-making.

When revealing his betrayal, Bundō displays a sly and cunning nature, using deception to his advantage. He exhibits obsessive tendencies, frequently cracking his neck and laughing in an unsettling, psychotic manner. His actions are driven by self-interest, demonstrating a willingness to betray even those closest to him without remorse. Additionally, he harbors a sadistic streak, deriving excitement from violence, murder, and gore, further reinforcing his ruthless and unhinged personality.

Branch of Sin
As a Deadman, Bundō Rokuro possesses the ability to manipulate his blood outside of his body, a power known as the Branch of Sin.

Unnamed Branch of Sin
Bundō’s unique Branch of Sin manifests as a hexagonal shield with protruding spikes along its edges. This shield is durable enough to block bullets, even from close range, making it a formidable defensive ability. However, the full extent of its offensive capabilities remains unclear, as Bundō primarily utilizes it for protection rather than direct combat.