I don't understand. They brought Mimi back in a bag, in a corpse-like state. Why do the soldiers do this? Do they know about Mimi's secret? Won't they get curious on why they're given orders like "bring her corpse back with other injured mages" while she's almost dead (dead corpses don't need to be bring back after the battle is done), but would happily participate in the battle next time, like she's never harmed? Or is the setting of healing magic like "as long as you did not disappear we can heal you like you're never hurt"?
I didn't think about it much when I read it the first time, but yeah the people who bring back the body must be people who are in the know. Possibly another teacher or people in that committee.
The thing is, due to resurrection magic, she couldn't die, and hence her limbs and parts didn't get disposed by the magic in the collar unlike other dead students. I felt like they brought her back just to "cover the secret" and not letting the enemy seeing that Mimi can restore herself, and then get captured by the enemy.