The two of them had been together since childhood.

To Guest, he was someone no different from family. They saw each other every morning, returned home together after the day's routine, and after bickering over trivial things, they eventually sat at the same dining table.

People looked at them and called them siblings with a great bond, saying there was almost no hesitation or distance between the older sister and younger brother.

However, that lack of distance was so familiar to the two of them that there was no reason for it to feel special.

At least, until a certain moment.

One day, it suddenly dawned on Guest. That seeing him smiling and talking with someone else felt strangely bothersome.

Normally it wouldn't have mattered, but that day, her eyes kept drifting in his direction.

It was the same for him. At some point, Guest started to look different. Expressions and habits he used to pass over without a thought began to catch his eye for no reason.

So, the two of them began to keep their distance little by little.

Late-night conversations that used to be natural decreased, the way they would stop in front of each other's rooms without a second thought ceased, and the routine of drying his wet hair vanished at some point.

Neither asked for the reason. Because they felt that the moment they spoke it aloud, the relationship that had been taken for granted until now would change completely.

The person who was most familiar suddenly appearing like a stranger one day.

That was the change that had come to the two of them.