Yoriichi Tsugikuni

Yoriichi is a tall man with a lean, muscular frame, fair skin, and maroon eyes. His long, wavy hair, tipped with red, is worn in a ponytail with shorter bangs framing his face. He closely resembles his twin brother Michikatsu but is slimmer with wavier hair. As the first bearer of the Demon Slayer Mark, a blood-red flame pattern spreads across the left side of his forehead and temple.

He dresses in a red haori over a pale orange kimono and black hakama, with red-strapped zori and white tabi. He carries hanafuda earrings made by his mother, which he later gives to his friend Sumiyoshi Kamado; they are eventually handed down to Tanjiro. In old age his hair turns spindly and white and his face gains deep wrinkles, though his strength never fades.

Yoriichi is calm, gentle, and reserved, wearing a solemn expression almost always and rarely showing emotion. So unreadable was his face that only his wife Uta could sense his feelings with ease. He regards the world as beautiful and considers it a blessing to have been born into it. Deeply humble, he sees himself as an ordinary man despite his extraordinary gifts and is unafraid to admit his own limits, even fearing for his life against Muzan.

Beneath the composure he feels deeply. After Uta and their unborn child are taken from him, he grieves for ten unbroken days, and the simple delight of a small child can move him to tears. As a boy he idolized his older brother Michikatsu and stayed silent for years, mistaken by his family for being deaf. When he later meets Michikatsu reborn as a demon, he weeps with pity yet still resolves to stop him.

Yoriichi is the strongest slayer in history, born already possessing the Demon Slayer Mark, the Transparent World, and the Selfless State, alongside a peerless physique and innate swordsmanship. At only seven years old, with no training, he overwhelmed a seasoned sword instructor on his first attempt. He alone managed to corner Muzan and very nearly killed him, leaving wounds that burned the Demon King at a cellular level for centuries and a fear of Yoriichi's very memory.

His Selfless State emanated no killing intent, drive, or hatred, making him almost impossible to detect or predict. He was the first to turn his Nichirin Sword bright red at will, suppressing even Muzan's near-instant regeneration. The Transparent World let him read the inner movements of a body and strike at the perfect instant. As a swordsman he was so unmatched that a six-armed training doll, the Yoriichi Type Zero, could only crudely approximate his technique.

His Sun Breathing was the original Breathing Style, later adapted by him into the five fundamental styles, Flame, Water, Wind, Stone, and Thunder, to suit students less gifted than himself. To slay Muzan he devised the Thirteenth Form, cycling continuously through all twelve forms to target the Demon King's seven hearts and five brains. Even in his eighties he cut down Kokushibo, the strongest Upper Rank, in a single motion before dying standing and unscathed. Yoriichi makes his full debut in Chapter 99 and Episode 45.