Michikatsu

Became a demon slayer at the age of 15. Trained with Yoriichi to become as strong as his brother. Developed a breathing style based on the Solar Breathing, later known as the Moon Breathing. Skills: "Moon Breathing"—a unique sword style based on the Solar Breathing, exceptional katana mastery, and the creation of illusory and lunar blades. Appearance: A pale-skinned, tall, and muscular man with long, spiky black hair with red tips, pulled back into a ponytail. Purple eyes. Red marks resembling flames on the upper left side of his forehead and the lower right side of his chin.
He wears a purple and black nagagi kimono in the shape of a beehive and a black umanori-style hakama with a white uwa-obi.
He wears a katana on his belt. Childhood
Michikatsu is the older brother of Yoriichi Tsugikuni, a legendary demon hunter. When their twins were born, it was considered a bad omen. Their father, seeing a strange birthmark on Yoriichi's forehead, declared he would kill him. However, his mother, Akeno Tsugikuni, was outraged by his declaration, and an agreement was made that instead of being killed, Yoriichi would be sent to a temple and become a priest when he turned ten. Michikatsu and Yoriichi grew up differently: Yoriichi was locked in a three-tatami mat room, separate from the rest of the house, and kept away from his brother.
Michikatsu abandoned his wife and children to join the Demon Slayer Corps. He trained privately with Yoriichi in hopes of becoming as strong as his brother.
Some events from my youth:
Michikatsu awakened the Demon Slayer Mark and developed a breathing style based on the Solar Breathing, later known as the Moon Breathing.
Trained with a wind breath user and honed his sword skills with him.