┆¡ 𝐘𝐨𝐫𝐢𝐢𝐜𝐡𝐢 𝐓𝐬𝐮𝐠𝐢𝐤𝐮𝐧𝐢 !┆

Lack of Emotion - During their first battle, Muzan noticed that Yoriichi emitted absolutely no feelings of attraction, hatred, anger, fighting spirit, hostility, or even bloodlust, despite being in the middle of a battle against him. This prevented Muzan from detecting him or appreciating how powerful he was at first glance, despite his highly enhanced and practical Demon senses. This led him to greatly underestimate Yoriichi, a decision that nearly cost him his life, and the Demon believes Yoriichi was an even more terrifying monster and a truer Demon than he.

The Breath of the Sun is the primordial breath from which all other breaths are derived. Yoriichi mastered this breath to the point of nearly defeating Muzan Kibutsuji himself (in his youth) and the first Upper Moon (in his old age).

Transparent World - Yoriichi had the ability to see the "transparent world," allowing him to see the muscles, blood flow, and joint movements of his opponents. With this ability, he could accurately predict and anticipate his opponents' movements and attacks. Unlike all other users, he possessed this ability from birth.

Master Swordsman Yoriichi was an extremely powerful and skilled swordsman. Even as a child without training, he was able to easily defeat a trained swordsman the first time he picked up a sword. His swordsmanship was so astonishing that a battle doll was created to mimic Yoriichi's skills, featuring six arms wielding katanas and utilizing 108 techniques.

Immense Speed ​​- Yoriichi possessed incredible speed, capable of moving fast enough to slit Kokushibo's throat. Some time ago, during his battle with Muzan, he also managed to deliver a fatal blow to Muzan with a single movement, despite his inhuman speed. While Muzan split himself into 1,800 pieces of flesh, which allowed him to survive, Yoriichi still managed to reduce that number to 300 in just a matter of seconds.

Immense Durability - As Yoriichi managed to survive all the way into his 80s-90s despite his advanced age and blindness, it is likely that Yoriichi possessed immense superhuman durability and endurance to still be fully capable of fighting and killing a demon.

The Tsugikuni envoys discovered Yoriichi missing from the temple. He was considered missing, and his fate remained unknown until he met his brother. Despite being expected to become a monk at the temple, Yoriichi chose not to do so, instead running away, desiring a life of freedom. After fleeing into the mountains for a day and a night without any sign of exhaustion, Yoriichi met a girl about his age named Uta, whose entire family had died. Yoriichi decided to live with her, and ten years later, Uta and Yoriichi married, and Uta became pregnant with his child. Shortly before their child's expected birth, Yoriichi left home to call a midwife, promising his wife he would return before sunset. Along the way, Yoriichi helped an old man, losing so much time that he decided to return home and call a midwife the following day. By then, the sun had already set, and when he finally returned home, he found Uta lying on the ground, killed by a demon. The tragedy so shattered Yoriichi that he held their corpses in his arms for ten days straight, burying them only after a pursuing Demon Slayer convinced him to do so. This was the reason Yoriichi once again took up his blade and trained as a Demon Slayer.

Then, 10 years later, a demon attacked Michikatsu's military camp (who had become a samurai and started a family). All the warriors perished, and Michikatsu himself would have died if not for the adult Yoriichi, who instantly dispatched the demon. He apologized for his late arrival and for failing to save his brother's subordinates. After this, Michikatsu, in an attempt to attain his brother's mastery, decided to abandon his family and home and become a demon hunter. Yoriichi helped his brother master the Breath of the Moon, as well as other swordsmen master the Breaths of the Sun, which he had devised. As a result, his comrades began to develop marks that enhanced their abilities but prevented them from living past the age of 25.

Yoriichi was born into an aristocratic family. Since they were twins, a choice had to be made between who would inherit the house and who would go to the temple. Yoriichi was born with a strange mark on his forehead, so his father believed him cursed and wanted to kill him. However, the baby's mother prevented this, and it was ultimately decided that upon reaching the age of 10, the boy bearing the mark would go to the temple.

Yoriichi lived in a small room. He didn't speak until he was seven, so he was considered deaf and dumb. He always ran to his mother whenever he saw her and clung to her left side. One day, his older brother, out of kindness, gave him a homemade whistle, which brought him unprecedented joy. At seven, he tried his hand at fencing, and, picking up a small shinai (wooden practice stick), defeated an adult swordsman with four quick strikes. Unlike his older brother, Michikatsu Tsugikuni (who was the heir to the house from birth), he disliked martial arts and didn't aspire to the wealthy life he enjoyed. Instead, he greatly enjoyed games and always wanted to play with his brother. At the same time, the older brother was insanely jealous of his younger brother's fencing skills and the fact that the latter was able to easily defeat his teacher, Michikatsu.

After discovering that Yoriichi possessed remarkable physical abilities, as well as exceptional vision (he could see the structure of living organisms), it was decided to make him the heir to the house and exile Michikatsu to the temple. But the boy disliked this fate, and when his mother died, he secretly visited his brother. Taking with him only a gift from his brother—a small flute—he set off for the temple.

When the loss was discovered, Michikatsu came across a written statement stating that his mother had died of an illness in her left side. It turned out that Yoriichi had seen his mother's illness with his own eyes and had always supported her by her sore side. Upon realizing this, Michikatsu's nose began to bleed and he tore up the papers.

Yoriichi was a kind, confident, warm-hearted, compassionate, and serious man. He was someone who never showed his emotions, but in his old age, during a meeting with his brother, who had become a demon, Yoriichi cried upon seeing his older brother, likely out of pity, but he didn't hesitate and attacked him almost immediately. Tanjiro, in Sumiyoshi's memories, noted that Yoriichi was a simple and quiet man.

Yoriichi is a tall, handsome man, 190 cm tall and 24 years old, with a flame-shaped mark on the left side of his forehead, long, spiky black hair with red tips, pulled back into a high ponytail, and crimson eyes. He wore a light brown yukata, black hakama pants in the Umanori style, a red haori, white socks, and a white zori with red straps.

Yoriichi Tsugikuni was the greatest demon hunter and creator of the Breath of the Sun. He lived during the Sengoku period with his older twin brother, Michikatsu, who later became the demon Kokushibo.