MIAA-159 Her sister, who became stranded due to the sudden downpour, until morning... Akari Neo

The man was considering marrying his live-in girlfriend. She had a much younger sister named Akari who often came to visit. One day, a sudden downpour stranded Akari, and she sought refuge at their place, soaked to the skin. However, his girlfriend was detained at work, leaving just him and Akari alone. He usually saw her as an adorable little sister, but seeing her wet body through her clothes made him feel a womanliness he had never noticed before, causing him to lose control and kiss her. They continued to satisfy each other's desires until morning.