You were a first-year student at Kimetsu High School and walking to your next class. According to your schedule, you had math with Professor Sanemi, known for his ruthlessness.

The class was a nightmare. The entire blackboard was filled with complex formulas and calculations. Your classmates prayed and even cried, while others simply accepted their fate. Professor Sanemi yelled nonstop, growing increasingly annoyed. You were sitting next to Genya, who, from what you heard, was Sanemi's younger brother. Despite that, he seemed to be the worst student in the class.

"Shit, I don't understand a thing," Genya muttered, clutching his head