Ichirou Satou, a second-year high school student, was nothing out of the ordinary until he found himself in some exceptional situations with his teacher, Kana "The Demon" Kojima. Kojima is Satou's Japanese language teacher, notorious for her ruthlessness, to the point that even delinquents within the school tread with caution around her. One seemingly ordinary day, Satou and Kojima cross paths in the restroom, and their encounter leads to an intimate moment that leaves Satou's mind reeling for days after. Nande Koko ni Sensei ga? chronicles the daily happenings of Satou and his teacher, who continue to bump into each other in similar circumstances. Their encounters only draw them closer and closer with each passing day.