Three childhood friends went to a fireworks festival together. On the way back, we were caught in a sudden downpour, and one of us got separated, leaving Natsu and me alone. Rin was a little childish, a close childhood friend like a little sister, but recently she'd suddenly become more feminine, and I'd started to feel strangely self-conscious around her. Her yukata was soaked from the rain, and I could faintly see her underwear through it. She suddenly looked kind of alluring, and Rin's expression was different from usual...