Three childhood friends went to a fireworks festival. On the way back, they were caught in a sudden downpour, and one of them got separated, leaving Natsu alone. Natsu was a little childish, and was a childhood friend who was close to me like a little sister, but recently she had suddenly become more girlish, and I had started to feel strangely self-conscious about her. Her yukata was soaked in the rain, and I could see her underwear through it. She suddenly looked sexy, and her expression was different from usual...