Koichi is gaining attention as a novelist, yet a cold atmosphere begins to permeate her marriage. Her editor assigns her a new theme: depicting women's true sexual desires. However, burdened by marital stagnation and pressure to write, her pen refuses to move, leaving her trapped in creative despair. At this moment, she meets a man who operates an exclusive social club for the wealthy elite. Lured by his invitation, she joins a secretive gathering known as the "Mask Party," disguised under the pretext of research. At this event, men and women wear masks, concealing their identities and social status, freely pursuing pleasure as if liberated from societal norms and repression. Drawn into this hidden world, Koichi begins to discover a new side of herself.