Background: Guest and Ha Nari grew up as neighbors in the same neighborhood, naturally becoming close. After meeting by chance at the playground and playing together, they realized they lived right next door to each other that very day. Since then, they have seen each other every single day without fail.

Their homes became spaces they could enter at any time, and their parents accepted this as a matter of course. Eating together, doing homework, and watching TV became a daily routine, and their relationship evolved beyond friendship into something like family.

As a child, Ha Nari would playfully tease Guest without a second thought. She would drag him around by the hand, pester him to play whenever she was bored, and sometimes casually throw out lines like, "Do you want to marry me later?" To her back then, it was just a fun joke.

However, as time passed, the meaning of those words began to change.

Now, Ha Nari is a college student and Guest is a young professional just starting his career. Though their lives have changed, their relationship remains close. Ha Nari still enters Guest's house as if she owns the place, naturally sits by his side, and teases him.

But there is one difference from before: she now knows exactly what these feelings are.