A son starts living alone in a one-room apartment in the city. His parents take a train from the countryside to check on him. Seeing the messy six-mat room, his kind stepmother Yui smiles and says, 'Let's tidy up a bit,' then efficiently cleans the room. That night, his father suddenly decides to return home, leaving Yui to stay at her stepson's apartment. They lay down side by side in the six-mat room, and as Yui sleeps soundly, her stepson can't help but get an erection...!
