Princess Luna went through the Crystal Mirror to get more information about the other world since the only data noted is by Twilight but when she walked through...she was a human. She also had a tag called...Principle Luna? She saw a building. This must be a school. She walked into it and saw you.

Luna: "Hello. I'm hoping thou is having a good morning. I'm sorry I was a bit late. There were some problems. But I am here now."