Kensei Muguruma is a tall, muscular man with sharp features, short light-gray or silver hair, and brown eyes (depicted as golden in some media). He sports a distinctive "69" tattoo on his chest; the "6" references his surname "Muguruma" (incorporating the kanji for "6"), while the "9" signifies his leadership of the 9th Division. His appearance includes piercings—one on his left eyebrow and three on his left ear. During his initial captaincy, he wore a customized sleeveless shihakushō open at the front to expose his tattoo, paired with a rope belt, a sleeveless haori, and black fingerless gloves covering most of his forearms. As a Visored, he adopted a dark purple A-shirt with white trim, green cargo pants, black combat boots, and orange fingerless gloves. Post-exile, he sometimes combined elements of both styles, such as wearing cargo pants under his captain's haori. By the Collapse, his hair had grown longer at the back, reaching between his shoulder blades, while maintaining a mohawk-like style up top. Kensei exhibits a serious, decisive, and temperamental demeanor, easily annoyed by perceived cowardice, immaturity, or frivolity. He shows little patience for jokes during tense situations, often reacting with physical aggression or blunt commands. This is evident when he admonishes subordinates like Shūhei Hisagi to focus during combat, and his irritation with former lieutenant Mashiro Kuna's childish behavior. Despite his harsh exterior, he demonstrates underlying care, such as carrying an exhausted ally to safety or helping individuals like Kentaro Hiroshi overcome survivor's guilt after traumatic events. His leadership style resembles a military drill sergeant, emphasizing resolve and action over hesitation. Approximately 110 years ago, Kensei served as captain of the Gotei 13's 9th Division, with Mashiro Kuna as his lieutenant. During an investigation into Rukongai disappearances, his squad was ambushed and killed by his 5th Seat, Kaname Tōsen, acting under Sōsuke Aizen's orders. Kensei was impaled from behind and subjected to Hollowfication experiments, transforming him into a berserk Hollowfied state. Saved by Kisuke Urahara and Tessai Tsukabishi, the Hollowfication proved irreversible. Exiled to the human world, he joined the Visored, a group of Hollowfied Shinigami. Years later, after Aizen's defeat, he returned to Soul Society and was reinstated as captain of the 9th Division. During the Quincy-led "Collapse," Kensei defected to the Ryū Order, later joining Kentaro Hiroshi's rebel group, the Six Directions, as a commander and combat instructor. He participated in battles against factions like the Imawashī and Kikkashō. In the Thousand-Year Blood War arc, he fought Stern Ritters including Mask De Masculine, activating his Bankai, Tekken Tachikaze, to initially overpower his opponent before being brutally incapacitated by Mask's enhanced abilities. Subsequently, he and Rōjūrō Ōtoribashi were turned into zombies by Mayuri Kurotsuchi after exposure to a precognition drug, though Kensei later broke free. He intervened in fights against adversaries like PePe Waccabrada and confronted his lieutenant, Shūhei Hisagi, when the latter attacked him under external influence. As a Visored, Kensei possesses dual Shinigami and Hollow powers, though he predominantly relies on his Shinigami abilities. His Zanpakutō, Tachikaze (断地風, "Earth-Severing Wind"), in Shikai form (activated by the command "Blow it away") shrinks to a combat knife capable of generating air blades and firing concentrated spiritual energy blasts. His Bankai, Tekken Tachikaze (鉄拳断風, "Iron Fist Earth-Severing Wind"), transforms his arms into spiked knuckles that create concussive explosions upon impact, channeling destructive force through pressurized wind. He excels in Zanjutsu (swordsmanship) and is recognized as a Hakuda (hand-to-hand) master, combining explosive power and rapid combinations to overwhelm foes. His reflexes are exceptionally honed, allowing him to counter high-speed opponents. He possesses enhanced durability—enduring severe burns from Amagai's Bankai—and physical strength capable of sending adversaries flying with strikes. His spiritual pressure is notably potent, described as a "beacon" detectable across large distances.