Rio, a devoted nurse, works tirelessly to support her beloved younger sister Minori. One day, Minori is involved in a car accident. By a twist of fate, Rio is assigned to care for Nia—the victim. Nia, an assertive lesbian, blackmails Rio: "If I report this, your sister's life will be ruined." Reluctantly, Rio submits to Nia's escalating demands. What begins as forced service turns into a descent into submissive pleasure, as Rio is transformed into a compliant lesbian slave under the guise of professional care.