The Start Of A Possibile Explanation

Midoryia was rushed to the hospital after Recovery Girl used her quirk.

All Might was pacing in the hallway in front of a surgery room, waiting for Midoryia to be transferred out.

"Toshinori."

"Inko."

"Where's Izuku?" Inko asked as she rushed over to the teacher.

"He's still in surgery."

"It was so bad he needed surgery? I don't understand what happened?"

As the two were talking, the doors to the operation room opened, and two surgeons rolled Midoryia passed All Might and his worried mother.

"The surgery was minor and successful," a doctor said as he walked out.

"The goop, what was it?" All Might asked.

"I had a sample sent to our lab to determine what it could be; all I know so far is that it is very acidic…"

"And?"

"The surgeons are passing him off to some of our best people in Radiology."

"Radiology?!"

"Whatever that substance was wasn't just acidic it was also extremely radioactive."

Back at U.A. Ectoplasm, Cementoss, Uraraka, and Todoroki followed Bakugo to his locker.

When Bakugo opened his locker, he took out three books he checked out from the school's library. When he took them, he walked to an empty wall.

"Why are we looking at a wall?" Uraraka wondered.

"Ochako, do you promise to keep secret what you are about to witness?" Cementoss asked.

"Yes?" She responded nervously.

"She won't tell," Bakugo said.

"IcyHot."

Todoroki locked the locker room door, so no one came in. He walked around, making sure no one was hiding.

"It's clear," he said.

Bakugo used his free hand and placed it flat on the wall, and he used his quirk to make hundreds of micro explosions within two seconds. The cement wall started to open, revealing an iron wall with a door and a keypad. Bakugo placed his thump on a reader and then entered a ten-digit code. After he did, Todoroki did the same.

"Number two: Katsuki Bakugo. Number three: Shoto Todoroki."

The Metal door swung open.

"Welcome, Ground Zero. Welcome, Shoto. Welcome, companions."

"What is this place?" Uraraka asked as they all walked inside.

"This is a room for U.A.'s big three. Only them and a few teachers know about it," Ectoplasm explained.

As the lights turned on, Uraraka was able to see everything. There were three motorcycles, each colored to match Bakugo, Todoroki, and Midoryia. There were cars colored the same.

Bakugo walked to the middle of the room and stepped on a button. Out of the floor wrose up a circular table. He placed the books on it and opened them to pages he had bookmarked.

He walked to an empty wall and pressed another button, then multiple monitors came out of the wall, and keyboards came from the floor.

"This is the craziest thing I've seen in this school yet, and that's saying something," Uraraka said in shock.

"I was looking at these books for more explosive substances," Bakugo explained as he returned to the table.

"While I was, I came across something in the book called energetic as I read more into it; it was about an accident at a mining hole in America back in old western times. A group of men were sent to a cave with multiple tunnels inside that was lined with gold, but one of the miners found a glowing green rock; when he hit it with his pickaxe, a green slime started oozing out but then exploded out of the rock completely covering him in the green slime."

"What was it?" Todoroki asked.

"Nothing. It was something new," he answered.

"What happened to the miner?"

"That part is weird."

Bakugo walked to the monitors and pulled up pictures of old newspapers from when the slime was found.

"A man presumed dead after being sprayed with an unidentified goo wakes up after autopsy."

Cementoss read off the headline, and after he did, Bakugo pulled up another article.

"The man woke up even though his intestines were taken from his body and all his blood was drained; my first thought was zombie, I was wrong, but also I was right."

"So there was a zombie apocalypse decades ago, but not anymore?"

"It's still going on," he said.

"There are zombies out there?!" Uraraka panicked.

"Not zombies, powers. They described a zombie apocalypse, but it was the man spreading what we now call quirks."

"What are you saying exactly?"

"That man… he brought quirks into existence."