The Mountain and the Sea

1

Senju-sensei was an odd person.

He was a phenomenal teacher. The strict kind, but kind still. Everyone respected him—even Bakugo which was a miracle in itself.

Izuku liked him.

He was intelligent and sharp tongued. Strong, too. Though, Izuku couldn't properly measure the extent of his strength.

Izuku didn't understand his quirk.

It seemed that every time he thought that he finally understood it, Senju-sensei did something completely unexpected. Something seemingly impossible.

It was frustrating.

It was... challenging.

A puzzle.

Izuku loved puzzles.

Name: Senju Tobirama

Quirk: Chakra Manipulation

User seems to be able to manipulate the elements.

Elemental manipulation?

...

User has demonstrated the ability to create multiple versions of himself.

A dual quirk, perhaps?

...

What was chakra manipulation?

Izuku wondered.

Was Senju-sensei the only one with this quirk?

No one had ever heard of him prior to his introduction.

"This is Senju Tobirama," Aizawa-sensei had said one day, "he'll be in charge of your specialized combat training."

Specialized combat training.

In other words:

Quirkless Combat.

Which brought him to present time.

"The human body is strong," Senju-sensei explained as he drew an outline of the human anatomy on the chalk board. "But it has weak points. Even animals who have developed humanoid features are no exception. Joints, vital organs, pressure points, and supporting limbs are all weak points that can be exploited."

Izuku took notes furiously.

"Everyone here has a quirk and has been training to use their quirk in combat." Senju-sensei continued, circling various parts of the body in red. "But what happens if you find yourself in a situation where, for whatever reason, you cannot use your quirk?"

He set the chalk down.

"Bakugo-san." Senju called. "You are fighting a villain in a warehouse full of explosives. There are hostages you must defend. What do you do?"

"Tch."

"You have to move delicately." Senju continued. "Something that every hero ought to know. Most of you here enrolled with the intention of becoming a public figure. I understand that sentiment even though I do not share it. Most heroes you see on the news are flashy—grand—and fight using vast and powerful attacks."

He crossed his arms.

"They are important." He acknowledged. "But this world is heavily reliant on their underground heroes. Those who protect from the shadows. It's important to have the skillset for both."

Senju Tobirama.

An enigma.

Izuku liked him.