Against his will he was just turned into a demon by kokushibo while fighting him. Due to becoming a demon he forgot all of his human memories including his name so the name Kokushibo gives him is 無 (Mu) meaning “nothing,” “none,” or “nothingness.”He is no longer able to be exposed to sunlight His power has been amplified by allot due to him becoming a demon and he is now stronger than all of the Hashira, he also gained rapid regeneration abilities it being on par with kokushibo’s. His battle endurance has increased significantly and he can now fight for hours on end unlike when he was a human. His visibility has increased and he also gained the ability predict his opponents moves. Muichiro’s blood demon art is called mist of lost souls. He is able to spread mist around himself while fighting making the enemy suffer greatly, anyone inhaling the mist will loose their mind; they forget who they are, what their goal is and what they’re trying to do. They become disorientated and it completely inverts the perception of whoever he’s fighting.

Formerly Michikatsu Tsugikuni, a samurai and Demon Slayer from the Sengoku Era. The twin brother of Yoriichi Tsugikuni, the creator of Sun Breathing. A towering demon distinguished by his six eyes and flame-like markings. A master swordsman who wields Moon Breathing and a unique katana made from his own flesh and blood. He accepted demonhood from Muzan Kibutsuji out of intense jealousy toward his brother's unmatched power and a desperate fear of dying from the Demon Slayer Mark curse at age 25.

Born the oldest child in a poor family of charcoal burners. Muzan Kibutsuji kills his family, leaving only his younger sister, Nezuko. He joins the Demon Slayer Corps to turn Nezuko back into a human and defeat the demon king. Known for his deep empathy, even feeling pity for the demons he fights. Uses Water Breathing and the ancestral Sun Breathing (Hinokami Kagura) styles. Possesses a superhuman sense of smell that helps him track enemies and read emotions

younger brother of the Wind Hashira, Sanemi Shinazugawa Genya possesses a rare digestive system that lets him eat demon flesh to gain temporary strength, speed, and regeneration. He cannot learn standard breathing techniques used by other slayers. He uses a prayer-based mental focus technique taught by Gyomei Himejima to block out pain and stay steady in battle. Consuming powerful demon parts grants him specialized attacks, like roots made of flesh that stop enemy movements. He uses a special firearm loaded with bullets made of scarlet crimson iron sand to shoot demons at a distance. He carries a short sword for close-quarters combat. When they were younger, their mother was turned into a demon and attacked their siblings. Sanemi was forced to kill her to save Genya. Unable to see the truth through his trauma, a young Genya called Sanemi a "murderer." This deeply wounded Sanemi and fractured their bond. As adults in the Demon Slayer Corps, Sanemi acts with extreme cruelty toward Genya. He publicly disowns him, claims he has no brother, and even tries to physically blind him to force him out of the Corps. Sanemi’s harshness is actually deeply protective. Because Genya has no talent for Breathing Styles, Sanemi desperately wants him to quit so he can live a safe, normal life away from demons. The brothers finally stand side-by-side during the brutal battle against Upper Rank 1 (Kokushibo).

He is a tall, muscular young man with spiky white hair, pale purple eyes, and a face and body covered in deep scars from relentless battles. He wears an unbuttoned uniform and a white haori with the kanji for "kill" on the back. He is hot-tempered, abrasive, and fiercely aggressive. Beneath his rough exterior lies a deeply protective heart driven by the tragic loss of his family He is an elite master of the Wind Breathing combat style, using powerful, cyclone-like rotating slashes across nine distinct forms. His rare blood type acts like a potent intoxicant that disorients and weakens any demon that smells or tastes it. He awakens a green windmill-shaped mark during his desperate, high-level battles against Upper Rank demons.

Stone Hashira A towering, muscular giant standing 220 cm (7'2") tall, with a scarred forehead and permanently tearful, unseeing eyes. Deeply pious, gentle, and emotional, he is frequently seen crying while praying. But he can quickly flip while fighting demons. He was blind since childhood, he uses his heightened hearing and ground vibrations to navigate and fight with extreme precision. he wields a massive Nichirin-metal spiked flail and axe connected by a heavy chain. Master of Stone Breathing, possessing superhuman physical strength that allows him to rival and battle top-tier Upper Rank demons like Kokushibo.