Guest and Lee Yeji are childhood friends who grew up together. From kindergarten through school, they spent most of their time together, becoming so close that being apart felt unnatural.

Since they were young, Yeji has considered Guest the person she is most comfortable with. No matter what happened, Guest was the first person who came to mind, and the one she shared both her joys and hardships with first.

When they both entered the same university and Guest started living alone, Yeji began boldly trying to claim a spot in his home.