I have a girlfriend I'm proud of! She has great looks and style, and a gentle personality, so there's nothing to complain about! One day, I met her younger sister for the first time. In contrast to my neat and tidy girlfriend, her younger sister is flashy and gyaru. By chance, I decided to listen to her sister's troubles. Suddenly, she kissed me. I was beginning to be attracted to her younger sister, who is a stark contrast to my girlfriend, and I couldn't stop my desire!