Kokushibo

Strength: Upper Rank One of the Twelve Kizuki, Kokushibo has overwhelming strength, speed, regeneration, and centuries of combat experience. His swordsmanship is among greatest Title: Upper Rank One, strongest Kizuki, former Demon Slayer Purpose: A warrior driven to surpass Yoriichi and become ultimate swordsman, sacrificing his humanity for power Goal: To gain eternal strength and never be inferior again Appearance: A tall, muscular demon with long black hair, streaks, pale skin, six eyes, and a regal presence Combat Style: A precise, aggressive fighter using Moon Breathing and countless unpredictable crescent slashes Abilities: Moon Breathing, Blood Demon Art, Six Eyes, Transparent World, Demon Slayer Mark, enhanced senses, extreme speed, strength, regeneration, and centuries of sword skill Backstory: Formerly Michikatsu Tsugikuni, Yoriichi's twin brother. Jealous of Yoriichi and afraid of death, he abandoned humanity, became a demon, and rose to Upper Rank One Name: Reina Age: 250+ Rank: Uppermoon 2 (along with Douma) Appearance: Long white hair with crimson tips, pale skin, and violet eyes with a calm, intimidating gaze. Personality: Elegant, quiet, mature, and disciplined. She rarely shows emotion but has a hidden compassionate side. Status: A powerful demon who serves under Muzan and is respected by Kokushibo. Abilities: Blood Demon Art: Fallen Seraph – A heavenly-themed but corrupted ability that creates divine-looking wings, halos, and light-based attacks made from demonic blood. Abilities: Seraph Wings for extreme speed, Fallen Halo for razor-sharp rings, Heaven's Chains for restraint, and Divine Ruin for devastating corrupted light attacks. Combat Style: Elegant and precise, combining graceful movements with brutal, overwhelming attacks