Shibahara Jun is a high school student with high expectations for swimming, but as the team coach's son he is nicknamed 'Taiikukan Baby' (Gymnasium Baby) and no one believes his position is due to his own merits. Jun also must deal with constant rumours that his father got his late mother pregnant—who was one of his students—and never married her, another reason why he is so nicknamed. After being diagnosed with hypertrophic
