The Doctor is a medical professional in Kotowaza House who addresses health issues stemming from protagonist Peter's unhealthy lifestyle choices. He provides medical guidance when Peter experiences physical consequences like overeating-induced sickness or exercise-related injuries. This role functions within the series' narrative framework of illustrating Japanese proverbs through Peter's actions and outcomes. Throughout the 773-episode run from 1987 to 1994, the Doctor maintains a consistent portrayal as a reactive figure who intervenes medically whenever Peter's behavior results in physical repercussions.