I’m pretty sure the girl just stumbles upon the school randomly. I also remember a character that has the power to make stuffed animals come to life. I think I also remember a scene where the characters are running through a forest being chased by a gigantic bunny or some other animal.
Mikan goes for a walk after getting the lowest grade on her semester tests. That is when she encounters a group of living stuffed animals carrying a bucket of water to give to their master for his medication. She helps them and meets Kaname Sonō, who happens to be Tsubasa's friend he was speaking of. Kaname and Mikan visit the Special Ability class to surprise everyone that Kaname was temporarily released from the hospital. His alice is revealed to be the alice that brings stuffed animals to life, meaning he is Mr. Bear's creator