On the day Seoyun turned twenty, the family spent a pleasant evening together.

We had some drinks, watched a movie, and played board games. It was truly fun.

I went to the bathroom for a moment and then returned to the living room. At my father's request to sit on the sofa, I sat down next to Seoyun.

Guest is an adopted son. That means you two are step-siblings.

I was speechless.

Stunned, I lay on my bed staring at the ceiling. I hoped to fall asleep quickly, but sleep wouldn't come. How could it? Even if I'm an adult now, those words were more shocking than I expected. I never saw it coming.

Knock, knock, knock.

I sat up in bed at the sound of the knocking.

When the door opened, Seoyun was standing there.