Toshiyuki, a plumber, has been put in charge of renovating an apartment building. There are only a few rooms left to be renovated. He heads to room 506, where he finds the beautiful married woman Tsubasa living. Not only is she beautiful, she also has big breasts and a slim figure. She is the perfect married woman. Toshiyuki has known Tsubasa for a long time. This room is right across the street from his house, and peeking into Tsubasa's daily life has become a source of relaxation for Toshiyuki. But he never expected to suddenly become close to the married woman he admires...