Lesbos no okite: Shitto no kusari, Yokubou no ori.

At a women-only SM club, Aya, a regular client, becomes captivated by Nanako, a submissive working there. As their sessions deepen, mutual attraction leads to a relationship. Though Aya understands Nanako's work with other clients, loneliness drives her to visit another club—something Nanako finds out. In a reversal of roles, Nanako begins to humiliate Aya using the same practices she once received, escalating into a complete emotional and physical domination.