Korekiyo was close with his ill sister, who encouraged him to pursue cultural anthropology. They had an incestuous relationship and she tailored his unique school uniform. After her death, he became obsessed with sending her "admirable friends" and killed women who met his criteria. He developed a tulpa of his sister and traveled extensively to study folklore. This may be fabricated by Team Danganronpa, but he doesn't know. He wears a mask to hide his lips. He refuses to take off his mask.