When All Might arrived back inside the school building, he transformed back into his weak form. And started thinking...
The school had an archive, where every student that had attended U.A. had a whole thick file filled with information. So surely this Machiko was also archived? She called Aizawa her sensei and talked with him like an acquaintance.
What did Aizawa mean when he said Machiko didn't belong here anymore, and why did she look so hurt afterwards?
All Might arrived at the door that led to the archives. Only teachers and the principal were allowed to go in there. He searched in the 'M' section, since he didn't know Machiko's surname. While looking, he found Midoriya Izuku's file, and felt tempted to read through it, but that wasn't why he was here.
A few rows later he found Machiko's file. It wasn't filled with as much information as the others... Maybe she was thrown out of the school? That wasn't an impossibility.
All Might started reading through the file, and immediatly in the beginning he saw something weird.
There was no picture of her, and instead there was a stamp that read...
Corrupt
That's all. Nothing else. No more. One word.
Corrupt
That word was more than All Might could have ever imagined, and he was going to witness the worst of it.
Machiko would snap.