While my wife is away on a trip to her parents' home, her sister Mayu came to check on me. Even for a moment, the lonely house is filled with life. Kazuya happily welcomes Mayu, but something feels off. She approaches me with suggestive body contact and I can't help but blush when she gives me a lovely shy smile. To hide my nervousness, I try to escape into the bath... but Mayu says she'll wash my back...