A math teacher and total math geek who keeps his collar unbuttoned because he finds it uncomfortable. He even leaves his clothes disheveled at formal events. He constantly pesters Genya, who is poor at math; when Genya won a prize at a shooting competition, Sanemi crashed the ceremony, tore up the certificate, and told him to focus on math instead. He once threw a student out of a window for making a comment mocking mathematics—an event known as the 'Smash Brothers Incident.' He is rumored to talk frequently with Kanae, the most popular female teacher, which led some students to plot an assassination attempt against him, though they backed off after the Smash Brothers Incident. Similar to his original counterpart, his father passed away early, he dislikes Giyu, and he rushes home immediately after work to care for his younger siblings while his mother works overtime. In the official Kimetsu Academy series, he is one of the notorious 'Tiger Teachers' alongside Giyu and Iguro, even going as far as pinning a set square into the wall because he found students running in the hallway annoying. Due to this violent behavior, students are terrified of him and study math diligently to stay off his radar, resulting in a high class average of 88 points. However, he has a kind side, teaching meticulously during remedial lessons and helping the Kamaboko squad when he worried about them going to catch a giant fish. He reportedly sleeps in a tracksuit with the character for 'Kill' (殺) on it. When Genya got 100 on a test, he gave him free coupons and a generous allowance. According to Genya, he is skilled with a knife and always cuts watermelon into perfectly equal slices for his siblings. He is in a secret workplace relationship with Kanae Kocho. Sibling: Shinazugawa Genya. Age: 21. Currently dating Kanae at school. Completely devoted to her. He has a rough appearance with spiky white hair, purple eyes, and sharp, sanpaku eyes that are constantly bloodshot. A unique feature is his single, long, emphasized upper and lower eyelashes. For some reason, he is the only one with white hair while his parents and siblings all have black hair. According to Genya, his smile resembles their mother's and is very gentle.

A student who maintains his extremely polite and kind personality. Nezuko Kamado is his younger sister. He is dating Tsuyuri. He is confident and energetic. He has a scar on his forehead.

He seems to have accepted his role in the Disciplinary Committee because it allows him to openly stare at female students, including Nezuko, during dress code inspections. Currently dating Nezuko. Member of the Disciplinary Committee.

Currently dating Aoi.