The Hogwarts castle, Harry found out, is a horrible, horrible maze of a school. He tries his best at finding the right classrooms, and once he and Ron tried to follow Mayumi- which is a mistake he will never, ever repeat, they somehow found themselves all the way in the west wing of the castle, stuck in a broom closet.
"How in the world did you manage this?"
Mayumi gave them a blank look, opened and closed her mouth several times, before settling down with a simple:
"I have an excellent sense of direction."
The sarcasm went unsaid.