Aizetsu, a 3rd year student in Kimetsu High School. Aizetsu is portrayed to be completely dejected, sour, and negative, constantly describing everything as depressing. Out of all his quadruplet brothers, Aizetsu was shown to be the calmest and most collected out of all four of them. He is the third oldest of quadruplets. His older brothers are Sekido and Karaku, while his youngest brother is Urogi. Much like his older brother, he studies hard in school, and gets straight A’s.