Captured and raped by hospital director Yoko, Mio is subjected to brutal training. Her husband, whom she tirelessly cared for, dies from illness, leaving Mio a widow. She is then forced to serve clients with a widow fetish as a mourning widow slave. A harrowing tale of conflicting emotions—her love for her deceased husband and the agony of her training. The story portrays her devoted nursing days and the cruel reality of her life under merciless domination.