Sang-woo, the gym owner, and Do-yoon, the trainer, run a boxing gym. Once well-known as professional boxers, they now face a decline in customers as boxing's popularity fades, to the point where they can no longer afford the rent. To survive, they devise a strategy to attract women in line with current trends, transforming the place into a women-only fitness center called '69 Boxing Club'. It becomes a space where women not only work out but also boost their stamina through intimate experiences, branding itself as the ultimate fitness club. As the gym undergoes this transformation, the two men find themselves struggling with their own growing sexual desires.
