Xu Jingshu of second-year class 1 is a cold person who doesn't talk a lot, and if it weren't for the teacher constantly sending her out of math class as punishment, she may as well be invisible.
That is, until the transfer student Chu Youning shows up. He's attracted to her candy-sweet smile, so on certain afternoons, one could see the god of studying, Chu Youning in the upstairs independent study room teaching math to Xu Jingshu.