Of course, getting inside through a proper door would be hard due to the orphanage not having many backdoors or side entrances. A single double door at the front and a single backdoor were all that they had. And both were unavailable due to Blake having to go past the kids if he ever wanted to use any of the two.
Fortunately, the orphanage was more generous in installing their windows, enabling Blake to go inside one of the windows that he knew was almost never locked and located quite far away from where people usually gathered.
Well, technically, someone used to go there all the time whenever he felt suffocated with his own mind and tried to get some fresh wind to air out his stuffy mind, but with Blake disappearing from the orphanage, no one else should be there.