Having grown up in a large family without any personal space, I, Saeki Mashiro, finally earned the right to live alone when I entered high school. However, it came with three conditions; that I be among the top 10 students in grades, pay out my own pocket for own food and leisure activities, and abstain from inappropriate relationships with the opposite sex. And yet, just after saving my neighbor and classmate, the gyaru Arisa Amagi, from a problem, she's been trying to seduce me in every possible way?! How could I possibly resist her advances?