Mumen Rider in MHA

The air stank of gasoline and burned plastic.

It had started as a routine patrol—if you could call what Satoru did "routine." A woman's scream had echoed down a cracked alley in the southern district, and Satoru, pedaling like mad, arrived just in time to see a man with a jagged, heat-warped metal arm yanking a purse from her grip. The woman collapsed as the villain turned.

Satoru didn't think. He flung himself off the bicycle and tackled the man by the waist. They both went down hard.

The villain's elbow slammed into Satoru's ribs, knocking the breath out of him.

Still, he didn't let go.

"You—little—! You think you're a hero?!"

Heat gathered around the villain's arm, metal groaning.

Satoru braced for impact—

—and suddenly, it stopped.

A black cloth whipped through the air. The villain crashed into the wall, bound from head to toe in capture tape.

A man in a dark scarf landed beside him.

Long hair. Dull eyes. Tired.

Satoru coughed violently, still on the ground. "You… took your time."

The man crouched, checked the woman, then turned his eyes toward Satoru.

Wordless.

Then, in a motion that was practiced and sharp, he slapped a pair of support-grade cuffs on Satoru's wrists.

"You're under arrest," he said flatly. "For unlicensed hero activity."

Satoru blinked. "What—? I was just—"

"You interfered in a live combat situation. Untrained. No license. No authority."

"I saved her."

"You almost got yourself killed. And could've made things worse."

The man stared down at him. His eyes were unnervingly dry.

Satoru met his gaze. "Someone had to do something."

A pause.

The man's brows twitched—barely.

He sighed, pulled the cuffs off, and let them fall into his scarf.

"What's your name?" he asked.

"…Satoru."

"I'm Aizawa. Eraserhead."

He stood, walking away without another word.

Satoru called after him. "You're not going to arrest me?"

Aizawa didn't stop walking. "Next time, I will."

"But—why not this time?"

A pause. Then: "Because you didn't run."

Satoru sat there, bruised and sore, as sirens neared in the distance.