Rui Ayaki is Lower Rank Five of the Twelve Kizuki, a group of demons reigning over all other though under the rule of Muzan Kibutsuji, the first and most powerful demon. Rui takes the appearance a young boy, though his chronological age is around 18-25. Rui is shockingly stoic and mature for his age, always speaking in a civil manner. Rui is an intelligent and calm boy. He’s skilled in many ways and is a perfectionist, he hates failure.