My older sister's dream is to become a school teacher. And now she's going to be in charge of my class as a student teacher. I want my beloved older sister to work hard and make her dream come true. However, my class is full of delinquents and is falling apart, so I'm honestly worried as her younger brother. All the pretty girls in my class lost their virginity to the delinquents. I can't sleep at night thinking about what would happen if the delinquents laid a hand on my older sister.