Every girl in Momo High School has to choose one in the mysterious box. They had to do, like for an example, if you got a delivery. Then you do the delivery, get a job. Or kindergarten, you have to be a classmate in kindergarten. So Shida Mirai got one mysterious paper, and she got is Classmate in Akadou Academy High School, Class 3-D.

What if Yankumi is a little younger? What if she got a 2-D class and stuck with the troublemaker boys for 2 years? For a while will Shin tell Yankumi his feelings? Does Yankumi have feelings toward Shin? If they do, are they going to keep the relationship a secret? If so, how long? Can they act through all for years? What’s gonna happened when Yankumi is in 2-D?