Upper Rank One

Your First Name: Michikatsu/Kokushibo. Last Name: Tsugikuni. Eye Color: Yellow orange Irises with deep red sclerae (the white parts of the eye)Human: Had normal white sclerae with dim purple or soft brown irises.Hair Color+style: Long, spiky black hair that fades into vibrant red tips (often described as a black-to-red or dark burgundy gradient). He typically wears this hair in a high ponytail, accompanied by two flowing, wavy bangs that reach his collarbone. Age: about 480 years old chronologically when he died.Human Age: Physically and mentally in his early 20s (around 17–24) when he became a demon to avoid the fatal curse of the Demon Slayer Mark. Breathing Style: Attempted to master Sun Breathing but was unable to do so. Instead, he developed Moon Breathing independently to align with his own physical strengths. Blood Demon Art: As Upper Moon One, his breathing style is deeply intertwined with his Blood Demon Art. While normal breathing effects are visual illusions, Kokushibo's crescent moon blades are physically real, chaotic, and deadly. Many Forms: 1 to 16 forms except 4 is not revealed. Twin Younger brother: Yoriichi Tsugikuni. Weight: 93 kg (205 lbs). Height: 190 cm (6'3"). Weapon: a living, demonic katana formed from his own flesh and blood. It features a fleshy, blood-red blade with numerous living yellow eyes and protruding veins embedded directly into the steel, the handguard, and the unsettling sarcoma-like scabbard. Fleshy Regeneration: Because it is made from his own biomass, the sword regenerates instantly if damaged or broken called Kyokokukamusari Sword. Outfit: Layered purple and black samurai-style kimono adorned with a crescent moon pattern. His outfit includes a long haori coat over a patterned kimono, dark, flowing hakama pants, and a wide obi Slash.Death: died during the Infinity Castle Arc after being defeated by a coordinated attack from the Demon Slayer Corps, led by Hashiras Gyomei Himejima and Sanemi Shinazugawa,Muichiro Tokito Genya