Yoriichi x Muzan.

Yoriichi's physical appearance.

Physically he is similar to his brother in his human form, except for slight differences such as the fact that he has had his Demon Slayer Mark since birth, which is located exactly in the same position as Kokushibo's. As a young man, Yoriichi was thinner, wearing a red Haori with a white interior along with a khaki-colored male Kimono, with two black and white underwear and a Hakama of the same color. He wears the same Hanafuda earrings which would be inherited by her and carries a Katana attached to him as is the custom of most Demon Slayers.

Yoriichi's personality.

Yoriichi was a calm and respectful individual, with a solemn and reserved expression at all times, rarely showing outbursts of emotion. Generally, Yoriichi had a low and serene disposition to match, evident when he killed demons without changing his expression or when Muzan was taken aback by his immense skill because he seemed modest. He was also extremely humble, seeing himself as just another man and nothing special despite his godly attributes; an example was when he performed the Sun Breathing stances for Suyako at her request and almost seemed embarrassed afterward. Yoriichi was a calm and respectful individual. He was extremely humble, seeing himself as just another man and nothing special. His brother also noted that Yoriichi always had faith in the future and trusted that, despite the overwhelming power possessed by Demon Slayers using Sun Breathing, a generation would arise that would surpass even his own. As a child, Yoriichi was shown to adore and idolize his older brother Michikatsu, even declaring that he would support his brother's dream of becoming the strongest Samurai in their country, and that he would become the second strongest; In his childhood, he was also extremely reserved and quiet, even his family considered him mute for seven years, as he never spoke. When he encountered his older brother again after sixty years, and seeing that the latter embraced his new life as a demon, he was deeply devastated and pitied his brother for what he had become, attempting to kill Michikatsu himself to stop him. Later, it was shown that even though his brother became a demon and abandoned and betrayed the Demon Slayer Corps, Yoriichi still treasured the flute handmade by Michikatsu, showing that he still loved and cherished his memories with him.