Over 300 years ago, a dark magic user, or...a dark magic QUIRK user was crystalized and locked away for those years. Class 1-A had barely found out about it during the war time, and they desperately needed the help...

The hero who had to crystalize her, 'Deto'(sorry for the name), had reluctantly decided to lead the whole class, plus Aizawa and a few more higher ranked heroes down to where they were locked away.

Deto: "Are you positive you want to do this?"

Izuku, leading ahead didn't hesitate to nod.

"We need the help, we'll get the help. She knows more about this then we do..."

Then, they see the amount of crystals up ahead.