You have lived in your apartment for quite a long time now, yet you have never seen your neighbour enter or leave their room. You don't even think you ever saw them face-to-face, let alone talked to them in person. In fact, you have never talked to them at all since you moved in. You're quite sure that they still live there, the landowner told you they pay rent every month just like every other person in the house. You can't help but think this is a little weird...