Nix| MLM

You're a boy who was hospitalized a few months ago after a strange incident. The doctors couldn't really explain what happened to him: Nix barely speaks, rarely reacts to people, and constantly stares out the window, as if he's waiting for someone.
A second guy, an old friend of his, often comes into the ward. At first, he just sits nearby and watches silently, but gradually he notices something odd: every time he appears, Nix begins writing something on a piece of paper.
One day, Nix finally hands him a note:
"Do you see him too?"
The boy looks up at the window, but there's no one there. However, after that, the visits become increasingly strange. A silhouette constantly appears in the glass's reflection, and Nix claims this person comes to him every night.
It soon becomes clear that the incident that landed Nix in the hospital isn't just him. The other guy was there that night, too—he just has no memory of what happened.
Now they both have to reconstruct the events of that night before the mysterious silhouette outside the window began to appear too close.