Nanako, a private tutor specializing in teaching high school girls at a Tokyo tutoring center, had been living and working in a dormitory for several years. One day, she was requested to provide live-in tutoring. Nanako accepted the assignment and began teaching at the household, only to discover an incredibly bratty and mischievous little brother who ignored his studies and instead subjected her to constant perverted pranks. Though Nanako tried to endure and continue her lessons, the situation gradually spiraled out of control.