My favorite childhood friend. I haven't seen him for a while when I grew up. One day, a childhood friend of a sister who went far away returned to her parents' house after a long absence. While talking about the old days, I still remembered that I had always liked my sister. I couldn't control my feelings, so at least for the past few hours, I wanted you to be my only sister like I used to be. My sister, who was confused at first, gradually began to feel...