Weeping Willow

At some point in the story, a young guy enters the house. He seems to be talking to himself. At this point, Sofia is upstairs taking a shower. He goes upstairs and looks through a keyhole. The view shifts to the keyhole and Sofia appears through the view of the keyhole with her towel wrapped around her. She does not notice that he is there. When the young guy goes downstairs again, this achievement unlocks.