"Because that way, it all makes sense. ...Back in the dining hall, Battler's parents weren't dead. One of them killed Aunt Natsuhi and Uncle Krauss, locked the door from the inside, and waited in that room. ...The other one took over the murders after that. ...To break open the closed room of the guesthouse, they needed to have an accomplice inside. That was Battler. ...That explains everything."