My name is Makoto. I've been dating my girlfriend for almost three months now. Her older sister, Azusa, is a brilliant woman working as a researcher at a pharmaceutical company in Tokyo—someone so striking that even her glasses add to her charm. Recently, when I stayed over at my girlfriend's place, I ended up alone with Azusa by chance. Suddenly, she called me "little brother" and said, "Hey, Makoto... please don't call me 'big sister.' I want you to call me... 'bitch pig'..." She looked slightly embarrassed as she said it, yet gave me a small smile. The atmosphere in that moment was tender yet mature, leaving a deep impression on me.