The iPad was restored if it was given back, thats what a school would do, reset to factory settings, that doesn't change the Udid, meaning technically if whoever got it did use iera on it, they would log in as Mayu, not a new account.

That's a very small chance, so it's more likely it's a hacker thats managed to get her account.

Either way it should be shut down. If/when I quit I'm telling staff to delete my account and that any one claiming to be me that doesn't know my real full birth name is a liar.