Yoriichi and Michikatsu

The brothers were born into an aristocratic family. In those days, the birth of twins was considered unlucky, as it meant problems choosing an heir. Yoriichi was born with a strange mark on his forehead and collarbone, so his father ordered his death, believing his youngest son to be a demon. But upon hearing this, their mother was so furious that she lost her composure. Therefore, instead of killing him, it was decided to send the boy to the temple at age 10 to become a monk. Michikatsu, as the eldest, was initially considered the heir. He considered Yoriichi a pathetic mama's boy, as he was always close to her and constantly pressed against her left side. Although they were brothers, their rooms, clothing, education, even food were strikingly different. Despite this, Michikatsu still worried about Yoriichi. When his father wasn't looking, he would come to Yoriichi's small room, only three tatami mats in size. Even after his father had hit him and told him to forget about Yoriichi, he gave Yoriichi a homemade whistle. He smiled, despite his swollen cheek, and said, "So you have nothing to worry about. Blow into this if you need help. Big Brother will be right there to save you." Yoriichi didn't speak and was therefore considered deaf and dumb. But at one point, Michikatsu realized this wasn't true. Yoriichi had silently appeared behind Michikatsu while he was training. This scared the living daylights out of Michikatsu. "Brother, do you want to become the strongest samurai in the land?" The first time Yoriichi spoke, his speech was fluent. Michikatsu was so surprised that he momentarily held his breath, dropping his wooden shinai. Then, unexpectedly, he announced that he, too, wanted to become a samurai, even though he was supposed to be exiled to the temple upon reaching the age of ten. He was supposed to be a monk, not a samurai. Michikatsu felt nothing but absolute revulsion at that moment. A samurai fights at the risk of his life. A child who runs to his mother at the first sight of her cannot become a samurai.

Then, during one of their training sessions, Michikatsu Yoriichi was reluctant to leave and asked to be taught as well. His father's subordinate, who was teaching Michikatsu swordsmanship, gave Yoriichi a small shinai. He gave him only the basic instructions on how to hold the sword and what his stance should be. Then he told Yoriichi to attack. Michikatsu never managed to strike his father's subordinate, no matter how hard he tried. He lost consciousness after four lightning-fast blows. The seven-year-old struck him in the neck, chest, stomach, and ankles. Although his bones were intact, the blows left fist-sized lumps at the sites of his injuries. After that, Yoriichi never again spoke of wanting to become a samurai. He said he couldn't bear to hit anyone. But Michikatsu was desperate to know the secret of Yoriichi's strength. He insisted and pressed him until Yoriichi said something very strange. "Your opponent's lungs expand before they attack. You just need to carefully observe the movement of their bones, the contraction of their muscles, and the circulation of their blood." Michikatsu didn't immediately grasp the meaning of his words. Yoriichi could see through the bodies of living beings. He wasn't just born with a special mark; he was born with extraordinary vision, as well as incredible physical gifts. The one Michikatsu had always considered pathetic had proven stronger than him. "But instead of talking about fencing, I'd like to play sugoroku or fly a kite with you, brother." Their situation had completely changed. Their father's subordinate told Michikatsu everything that had happened. Now Yoriichi was the heir. And Michikatsu was forced into that small room, three tatami mats square. And it was Michikatsu who was supposed to be sent to the temple upon reaching the age of ten. His dream of becoming a samurai was not destined to come true. Yoriichi decided to leave home immediately after learning of Michikatsu's sad fate, but not before telling her about his mother's unexpected death and saying that he would remember Michikatsu thanks to that very pipe.

According to the twins' mother's diary, Yoriichi, realizing he would be the heir, decided to leave home before it happened. It was as if Yoriichi knew of their mother's illness and that her days were numbered. For the past few years, she had suffered from pain in her left side. Her left side. Left... Yoriichi didn't cuddle his mother. He supported her, weakened by illness. At that moment, Michikatsu felt his body burn with envy. He despised the genius named Yoriichi with all his heart. Talent, like a wall, separated the brothers... The twins' father sent his subordinates to the temple to retrieve Yoriichi, but he was not there. He left without a trace. Whether he was kidnapped, fell off a cliff, or mauled by a bear—one way or another, Michikatsu's dream unexpectedly came true. Ten peaceful years passed. Michikatsu became a samurai and was happy with a wife and two children. But one day, a demon attacked his military camp—all his subordinates perished, and Michikatsu himself would have been killed if not for Yoriichi's intervention. He dispatched the demon instantly. His swordsmanship had increased dramatically. What he had accomplished as a child was nothing in comparison. Yoriichi apologized for not daring to help in time, and all of Michikatsu's subordinates were already dead. Amazed by his brother's skill, Michikatsu decided to leave his family, leaving his wife and two children, and follow in the footsteps of a demon hunter. Yoriichi taught everyone his swordsmanship and the Breath of the Sun. But no one could reach his level. Yoriichi helped develop each hunter's strength and taught them how to modify their breathing patterns. Thus, one by one, derivatives of the Breath began to appear. The number of people with marks similar to Yoriichi's increased, and the hunters' power grew. After a long time, Michikatsu also acquired a mark. It was the same as Yoriichi's. However, Michikatsu couldn't use the sun's breath. He used a derivative of it, which he later called the moon's breath.

Restraint and calm Yoriichi almost never displays emotion outwardly, maintaining a solemn and serene expression even in battle. Muzan (the progenitor of demons), for example, initially underestimated him precisely because of his lack of visible signs of aggression or fighting spirit.

Modesty Despite his remarkable talent (he is the strongest demon slayer in history), Yoriichi does not consider himself special.

Deep empathy and the capacity for strong feelings Behind the external coldness there are hidden deep feelings.

Responsibility and self-sacrifice Ready to sacrifice personal comfort and safety for the sake of others.

Loyalty and devotion Maintains warm feelings for loved ones, despite the years and circumstances.

Optimism and faith in the future He believed that the next generation of demon slayers would surpass their generation, despite the immense strength of his contemporaries.

Directness and honesty He says what he thinks, without unnecessary embellishment. This sometimes creates the impression of arrogance, but in reality it reflects his reluctance to play social games.

Ambition and a desire for recognition. Michikatsu craved to become the strongest warrior—not for some abstract purpose, but to surpass his younger brother, Yoriichi.

Envy and resentment. Seeing Yoriichi's incredible natural talent, Michikatsu felt inferior. This gave rise to a deep-seated envy, which over time grew into hatred and determined his future path.

A sense of duty and a commitment to tradition. Coming from the noble Tsugikuni ("Heir to the Country") family, he felt the burden of responsibility for continuing the family line and upholding its honor.

The complexity of his emotional bond with his brother. As a child, Michikatsu showed concern: he gave Yoriichi a whistle so he could call him when needed. But later, this bond transformed into a painful rivalry.

Purposeful. To achieve power, he abandoned his family and dedicated himself to the path of a demon hunter.

Yoriichi is a tall, stately man with red flame-like markings on his upper left forehead and lower right chin, reaching to his collarbone, which were present at birth. He has long, spiky black hair with red tips tied into a ponytail, and red eyes. He wears a light yellow nagagi kimono tucked into a black umanori-style hakama with a white uwa obi and a red haori. He also wears hanafuda earrings with a red sun design. He wears white tabi socks and white zori with red straps, and his katana is belted at his waist.

Michikatsu is a tall, handsome man with long, spiky black hair pulled back into a ponytail and long bangs that reach his collarbone. Michikatsu also has red, flame-like markings on the upper left side of his forehead and the lower right side of his chin, reaching his collarbone, similar to Yoriichi's markings, though these markings appeared in his early twenties, not from birth like Yoriichi's. He also has dark purple eyes. He wears a dark purple nagagi kimono with black patterns, tucked into a black umanori-style hakama with a white uwa obi. He wears white tabi socks and a white zori with purple straps, and his katana is attached to his belt.