NSPS-518 Sister-in-Law Spied On Shiho Sakura

Every year, my husband returns to his parents' house on the opening day of the sweetfish fishing season. My wife usually doesn't go, but this year she decided to tag along. Her father-in-law and brother-in-law live at her parents' house. However, her father-in-law is away on a three-day, two-night trip to a hot spring with his partner. Her brother-in-law is single and hungry for women. He sees his older brother's wife taking a bath...