Purpose of a Part-Timer: A female college student is working part-time at her father's laundromat business. One day she had an unusual laundry request: to have the laundry delivered to the customer's house. She carefully opens the door and enters the house, where she witnesses sex between a man, who appears to be the owner, and a woman. The female college student, who hides in the kitchen, watches the scene and is caught by the man while masturbating. A man who is having fun offers sex to her, who is in a state of excitement, and the atmosphere between them becomes luscious.