One is a sunny but a bit clumsy girl, and the other is a handsome and smart boy. They were born in the same courtyard across from each other. Their birthdays are only one day apart, but their ideological level is nearly a year apart.
It is said that you can't guess what a girl is thinking, so the two of them can be regarded as the real childhood sweethearts. Even if the boys are smart, they can't figure out this stupid girl.