Gyutaro

Gyutaro was a tall man with a pale gray complexion spotted with black blotches. His upper torso, arms, and legs were heavily muscled, yet his waist narrowed to a near-skeletal thinness. The pelvis protruded at an unnatural slant and the spine pressed visibly through his back, leaving him perpetually hunched. His narrow eyes slanted sharply downward, his green irises had dark orange centers, and his sclera glowed yellow-orange.

His unruly black hair shaded to lime green near the crown, worn messily with a tied top knot. Dark, ink-like blotches dotted his frame, while a streaming, water-like design ran across his face. He wore little beyond baggy gray-blue trousers and several pieces of patterned red and black cloth wrapped around his neck and arms. As a human he had the same facial blotches, a thin frame, poor hygiene, and pale blue, bloodshot eyes.

Gyutaro was cruel, spiteful, and consumed with envy toward anyone who had lived a better life than his own poverty-stricken past. He often offered a sarcastic compliment before viciously killing someone, and he would tear at his own flesh whenever jealousy or frustration overtook him. Having survived more than a century of battles, he grew arrogant and looked down on his opponents, sending Daki to fight first while he hung back.

For all his cruelty, he held a powerful, genuine love for his younger sister, whom he had raised himself after their mother's instability and death. That bond endured even after he became a demon, leading him to spoil and protect her. In his final moments he carried no regret for his own savage choices, but he deeply lamented his influence on Daki, wishing she had been raised by someone better and in kinder circumstances.

Recognized by Muzan as the genuine Upper Rank Six, Gyutaro was an immensely powerful demon carrying over a century of combat experience, having slain and devoured fifteen Hashira. He overwhelmed both Tengen Uzui and Tanjiro at once, and even after being effectively beaten he nearly killed all four heroes, stopped only by Nezuko neutralizing his poison. Muzan himself remarked the slayers would have died for certain had Gyutaro fought from the start.

His most dangerous trait was Core Detachment, removing his core in the form of his left eye and implanting it in Daki, which granted him immunity to ordinary decapitation. The siblings could only be slain if both heads were severed at the same moment. He wielded flesh kama and his Blood Demon Art, Haemokinesis, conjuring poison-coated sickle-shaped blades of solidified blood. Alongside flesh manipulation, immense regeneration, lethal poison, great durability, blistering speed, and overwhelming strength, these made him one of the deadliest foes the Corps faced.