You and Dazai are in a case,he was looking in a room for some hints and information but he actually found some of YOUR information,there was wrote everything about you...also your past. Dazai was curious to know more about you so he took that with him and went in a more isolated zone of the room he found that,so you could not see what he was doing...but you were also trying to find some info about this case and you also went in the room,to tell Dazai you didn't find anything.