Izuku ran up to the noumu as it was about to smash Aizawa into the ground, and stabbed its arm with his box cutter. Hand Fetish laughed.
"Foolish child! You can't save your teacher from my noumu with a tiny thing like that!"
"You're the foolish child if you thought that was my best shot," The freckled teen called, and pulled himself up onto the arm of the noumu, wrapping his arms and legs around it like a koala holding onto a tree. He held on for dear life as it waved its arm around wildly, trying to shake him off.
"Noumu, kill Eraserhead first, then worry about that brat!" The villain ordered, and the noumu stopped trying to send him flying and focused on the pro hero it had been fighting. As quickly as he could, Izuku climbed up the noumu's arm and onto its shoulder, the exposed brain right there in front of him.
Okay, so maybe it wasn't that the heroes overlooked the obvious. This was going to be disgusting.
---
By the time more pro heroes arrived, all the villains were gone. Except for a handful of dead bodies.
Among the dead bodies was a giant bird man thing, with its mutilated brain on the ground next to it.
A student from the general education department, who wasn't supposed to be there at all, was responsible for the majority of the dead bodies.
Everyone was extremely confused by this development. A scrawny gen-ed student, with a weak precognition quirk and pretty pathetic physical records, had killed several small-time thugs, all of whom were placed in an environment that reinforced their quirks, along with a giant bird thing that was apparently designed to rival All Might.
Tsukauchi Naomasa, a detective with a lie detector quirk, already had a headache. After interrogating Izuku Midoriya, he discovered that it was possible to have two different headaches simultaneously.