His mother is going on a trip, so his mother's best friend, Luisa, will be taking care of him instead. Koji's eyes light up at the rosy life he has suddenly started with Luisa. She has a refined, elegant face and a slender, curvaceous body. Koji wants to see her perfect naked body, which is hard to believe belongs to someone his mother is the same age as, so he tries to peek into the bathroom, but...he happens to see her fresh, warm underwear that she has just taken off in the changing room...