Hideaki is a man living in an apartment building. One night, he hears the lewd voices of the couple living next door from the window. He isn't particularly close to the wife, Erika, but he knows her somehow and imagines her in a lewd state. Hideaki is thinking about how he can do something naughty with Erika, and suddenly, his chance comes! When he goes to give her a thank you for always cleaning the common area, Erika appears without a bra...