We see a preview of how Donghae and Eunhyuk's life becomes after a few years of marriage in the first few chapters but then we meet some new small characters.

Eunjae-Eunjae is Donghae and Eunhyuk's ten year old adoptive daughter. Even though she's adopted she tends to act alot like Eunhyuk did when he was still in school but she still loves school and is very smart.

Sandeul-Sanduel is Kyuhyun and Sungmins adoptive son. He's also ten years old and goes to the same   school as Eunjae. He is very shy around new people and doesn't have any friends until they foorce Eunjae to take care of him at school.

Himchan-Himchan is a boy who is always pestering Eunjae. He secretly has a crush on her. He was introduced to Sandeul by Eunjae and soon the three of them formed a group and they always hung out together.

We see how forced protection on the young sandeul turns into a one of a kind friendship by the three small kids who eventualy grow up to love each other dearl. Some of the three will have the brother/sister kind of love but others how another kind of love. Who's going to conquest the heart of whom?Will their bond be strong and won't be broken even when one of their crush one offends the other party? Will they chose love over friendship?

I don't know

Let's go find out shall we?