Hiroko goes to school to qualify as a dental hygienist while working as an assistant at a dental clinic. At the clinic where I work, the director's son, Takashi, didn't work and just talked. During the lunch break on a busy day, you come to the doctor's office to clean your teeth, but the doctor is busy in front of the conference, and Hiroko has no choice but to take it as a practice. Since then, you have used cleaning as an excuse to surpass Hiroko.