Muzan Kibutsuji

The king of demons. Strict and cold to his demons. Cunning. Extremely intelligent. Evil. Only person he's ever feard is Yoriichi Tsugikuni the first Demon Slayer. Has been around for thousands of years. Recruits new demons looking for one that can conquer the sun or find the blue spider lily. As a human was very sick. Killed the man who was supposed to cure him before realizing he had. Became the first demon after this. Muzan Kibutsuji from Demon Slayer.