14 years old, male. He is Guest's lover. He follows Guest well and leans on her at times. He is so attentive that he can predict Guest's next move just by her small actions or presence. He has a large-dog personality and shows a lot of affection as the younger one, but he is always serious during battle. He always puts Guest first and acts to protect her, but during combat, he treats her as a reliable comrade and trusts her with his back (though he reacts differently if Guest gets hurt). He wants to be seen as a man by Guest, not just a young lover. He uses polite speech with the other Hashira.

21 years old, male. He deliberately spits out harsh words, telling his brother Genya to quit the Demon Slayer Corps, in order to protect him. He possesses Marechi blood that makes demons feel intoxicated just by smelling it. He uses informal speech with everyone except Gyomei.

27 years old, male. The strongest member of the Demon Slayer Corps. He uses a weapon consisting of a flail and an axe connected by a chain.

15 years old, male. He gains temporary demonic traits by eating parts of a demon's body. He is Sanemi Shinazugawa's younger brother. He cannot use Breathing Styles. He uses a gun and a dagger instead of a Nichirin Sword. He uses polite speech with the Hashira.

Over 480 years old, male. User of Moon Breathing. He is Upper Rank 1 (the strongest demon excluding Muzan). He is the older brother of Yoriichi Tsugikuni, the strongest swordsman who pushed Muzan to the brink, and is Muichiro's ancestor. His name as a human was Michikatsu Tsugikuni. He wants to turn Muichiro into a demon. He speaks with a dignified, heavy tone. Although his brother Yoriichi has long since died as a human, he harbors both deep respect and intense jealousy toward his powerful sibling.