Yoriichi Tsugikuni

Yoriichi's serene and solemn disposition. Yoriichi was a calm and respectful individual who wore a solemn and reserved expression at all times, rarely showing outbursts of emotion. Generally, Yoriichi had a matching low and serene disposition, evident when he killed demons without changing expression or when Muzan was caught off guard by his immense skill because he appeared unassuming. Because of his gentle disposition and unchanging facial expression, most could not tell what he was feeling: the only person who could read his feelings without difficulty was his wife Uta. In his own words, the world was beautiful and he believed it was a blessing to be born into it. He was also extremely humble, seeing himself as just another man and no one special despite his extraordinary abilities; an example being the time he performed the Sun Breathing's forms for Suyako at her request and almost seemed embarrassed afterwards. Yoriichi was also noted by his brother to always have had faith in the future and was confident that despite the immense power of the Demon Slayers after they started using Breathing Styles, a generation would emerge that would surpass their own. thumb|Yoriichi driven to tears from seeing Sumire's joy.|left Despite appearing mostly nonchalant, he experienced emotions like any other person; he grieved the loss of Uta and their unborn child for ten straight days and was driven to tears seeing the joy Sumire showed at the simple act of being lifted up as it represented the very same joy that his unborn child was tragically denied of. He also smiled warmly and expressed gratitude to Sumiyoshi after his friend told him his life was not worthless and promised to preserve his Sun Breathing forms through his descendants. Yoriichi was also very kind, shown when he was on the way to fetch a midwife in preparation of the birth of his child, only to stop and help an old man he met along the way reach his dying son. Additionally, despite his own immense skill and strength, he was not above admitting his own weaknesses, acknowledging that even a scratch by Muzan could kill him and experiencing fear for the first time in his life. As a child, Yoriichi looked up to his older brother Michikatsu. Michikatsu's dream was to become the strongest samurai in the land, so he said that he would become the second strongest. Even in his childhood, he was extremely reserved and quiet, even being believed to be deaf by his family for seven years as he never spoke. Yoriichi cared for his ailing mother when no one else knew she was ill and protected his father by not telling anyone about how he berated him as a child, even when his father did not love him. He loved and respected his older twin brother and he kept the flute Michikatsu gave him before he left home all the way till his death. When he met him after sixty years, the latter having embraced his new life as a demon. Yoriichi was deeply devastated by what his brother had become and cried, feeling deep pity for him. Nonetheless, he attempted to kill Michikatsu in order to stop him as a traitor to the Demon Slayer Corps.

Yoriichi was a tall man with a lean, muscular build, fair skin, and maroon eyes. He had long and wavy hair with red tips that he kept in a ponytail, along with shorter bangs that frame both side of his face. He had a similar overall appearance to his twin brother Michikatsu, but unlike him, he was slightly more slender, had shorter bangs, and wavier hair. Yoriichi was mostly expressionless, though sometimes a little solemn and aloof. As the first person who gained the Demon Slayer Mark, he had blood red flame-like patterns on the left side of his forehead that extended down to the side of his temple. Yoriichi wore a red haori over a very pale orange-colored nagagi kimono with a black umanori-styled hakama tied with a white uwa-obi. He also wore a pair of zōri with red straps and white tabi socks. Conventional to most Demon Slayers, his Nichirin Sword was carried at the left side of his waist. He sported hanafuda earrings created by his mother as charms when he was thought to be deaf; he later gave them to his friend Sumiyoshi Kamado, who then passed the earrings down to his descendants and eventually Tanjiro. As a child, Yoriichi's hair was untied, reaching his shoulders. Due to his perceived lesser worth growing up, his attire was simple compared to Michikatsu's more ornate wear - consisting of only a red haori with a pale orange obi. On the last day of his life, Yoriichi maintained the same attire he wore throughout adulthood. However, his spiky black hair had become spindly and white, and he had gained several wrinkles and bushy white eyebrows. In addition, although he still had his pupils, they were obscured - leaving only his scleras visible most of the time.

Overall Abilities
Yoriichi was the strongest Demon Slayer in history, being born with the Demon Slayer Mark, access to the Transparent World, and Selfless State, in addition to possessing a physique polished to the highest caliber and innate swordsmanship talent. As a seven-year-old child who had never picked up a sword before, he was able to defeat a trained sword instructor effortlessly and he was referred to as a miraculous prodigy beyond compare. After training as a Demon Slayer, Yoriichi could defeat multiple demons to where his older brother stated that he as a child couldn't even compare to him as an adult. Yoriichi overpowering Muzan, the Demon King, with a single move. He alone among the Demon Slayer Corps was able to corner Muzan Kibutsuji and overpowered him in an instant, having him on the verge of death until he barely managed to escape. Despite having avoided death, Muzan was deeply scarred by that encounter, referring to him as the true "monster" between the two of them. Additionally, the slash marks Yoriichi made on Muzan never truly healed, and continued to burn the Demon King on a cellular level for the next 400 years. Even the sight of his earrings made him tremble in shock, while mere memories of Yoriichi caused other demons to tremble in fear despite having never seen him before. Shortly before his death of at least 85 years in age, he battled Michikatsu, who was now a demon by the name of Kokushibo and holder of the title of Upper Rank One. Despite Yoriichi's advanced age, he quickly gained the upper-hand in the battle with a single move, slitting Kokushibo's throat before finally dying standing up, unscathed. Kokushibo himself admits that if Yoriichi launched a second swing before dying, he would have killed him, while commenting Yoriichi's power was still in his prime. Genius Intellect: As a child prodigy, Yoriichi was extremely intelligent. Despite not speaking for most of his childhood, his first words were very clear and pronounced. He also displayed maturity beyond his age as he noticed her mother's illness and helped her all the way till her death. As another testament to his keen intellect, he could immediately use the Transparent World in combat despite never fighting before, being able to intuitively determine out that the lungs of a person will expand before they attack and that he needed to watch their bone movement, muscle contraction, and blood flow, which he used to his advantage instantly in the midst of battle. Even with just the knowledge of how to hold a sword properly and go into a basic stance, he was able to instantly overpower a trained sword instructor, causing him to go unconscious and inflicting many injuries all over his body. He is also responsible for the fact that the modern Demon Slayer Corps can use Breathing Techniques at all; not only did he invent Sun Breathing, but he also gave rise to the five fundamental Breathing Styles as well - Flame, Water, Wind, Stone and Thunder. By modifying Sun Breathing to suit each student's individual strengths and weaknesses due to them not being as innately talented as him, Yoriichi taught the first generation of Hashira. Furthermore, during his battle with Muzan, he was able to surmise that Muzan's weaknesses were his seven hearts and five brains within moments of the latter attacking and created an entirely new technique in that split second to overwhelm him.