Mayumi works in an office job and has a side job selling underwear online. Her new product is see-through underwear, and she is at a loss as to how to sell it, but when she tries it on, she feels suspicious and comforts herself... One day, Mayumi is caught in a sudden rain shower and gets soaked. Of course, the see-through underwear she was wearing is also very see-through... Her neighbor Isejima happens to see her and is fascinated by how see-through it is! He takes Mayumi into his room without thinking...