By day, Mayumi works a regular office job, but she also runs a side business selling lingerie online. Recently, she started promoting a line of sheer undergarments, struggling to figure out the best way to market them. However, after trying them on herself, she unexpectedly became aroused and began using the lingerie as a tool for self-pleasure. One day, caught in a sudden downpour, her clothes soak through, making her sheer lingerie completely see-through. Flustered and drenched, she rushes to take shelter. Her neighbor, Isejima, happens to see her in that state, captivated by her transparent outfit, and impulsively invites her into his apartment.