At 21 years of age, Ninomiya Naoto is approached by a stunning woman who, out of nowhere, assaults him with a metal bat. Though he manages to flee, he finds himself on death's door the following day. Yet, destiny intervenes when he once again crosses paths with the woman, only to discover she's a doctor who specializes in the unconventional "batting treatment." She wields her bat, striking him, and to Naoto's surprise, he's instantaneously mended. Her unorthodox approach to healing profoundly impresses Naoto, and he resolves to become her assistant.