One day, Nanba Masato, a young man who is aspiring to be a writer, feels excruciating pain in his abdomen and is rushed to a hospital. A surgeon Okochi Yoko diagnoses him with appendicitis. Beautiful like a goddess, she eases his hellish pain. He is hospitalised after the successful surgery and delighted that she is his attending physician. However, this is the opening to great despair and doom. Yoko is sociable and cheerful and also treats patients kindly. But her true face is something that she cannot even personally understand. Apathetic to all events from a young age, she is impassive and immoral. She has no compassion when she sees people who are suffering and also no feelings of guilt. When target people or events materialise, her dark side will kick in on impulse.