A night alone with my wife's younger sister

Three days have passed since my wife left the house due to a trivial marital fight. Due to the rare approaching of large typhoons in recent years, I was already feeling more worried than anger. A few hours later, the chime rang. I opened the front door, suppressing my distraction, and found Tsubasa, my wife's younger sister, who was soaked, standing there. She came to care for me, but I couldn't take my eyes off her 'glossy wet hair... rainwater dripping from her jeans... wet and see-through underwear'.