The city lights passed quickly as the bullet train carried them closer and closer to Shibuya.

They were currently passing through Hosu, and Izuku had texted Iida to see if he was doing alright, but he had gotten no reply. In addition to Iida's lack of a response, he felt strange and out of place wearing his hero outfit on a train full of people.

He got looks from older people and uncomfortable admiring stares from younger children. It was like they thought he was greater than he actually was.

Izuku looked out the window at the city, "are you sure it's okay we're going to get in so late?"

Gran Torino waved flippantly and reclined in his seat, "There's sure to be more incidents at night. It'll be fun!"

Izuku thought about that, "I don't know about fun, but I think I get what you mean."

Izuku smiled, but his worrying got the better of him, and he checked his phone.

No text from Iida.

"Are you okay, Izu?" Himiko squeezed his hand gingerly, "worried about Mister Glasses?"

Izuku nodded, "I am. He hasn't said a thing in the group chat or responded to any of my texts."

Himiko smiled reassuringly, "I'm sure he's just busy with his own inter—"

An ear-shattering *BOOM* sounded from somewhere deeper in the city outside, and the train suddenly slammed to a stop.

"Passenger, please remain seated. We are making an emergency stop. I rep—"

The side of the train suddenly exploded inward, and through the debris came the body of a hero. Thankfully, he got up almost immediately after being thrown in.

"Who is this guy?!" The hero yelled as a large and lanky figure peered in through the hole that had been made in the train.

It was large and hunched, with thin, gangly arms and legs. It had four eyes and… an exposed brain.

'Nomu! Protect Himiko!'

Izuku's body moved on autopilot. One for All roared to life, and his heart pounded. He slammed into the train's roof and then right at the creature.

His bone-shattering kick met Nomu's jaw, and it was sent tumbling down to the street below.

Izuku blinked, "what?"

Gran Torino and Himiko stepped up beside him and looked down at the creature.

"Damn, kid. I think you knocked it out cold. Good instincts." Gran Torino smacked him so hard on the back that Izuku was almost thrown out of the hole in the train.

Izuku just looked down in awe, "I just… moved. I could only think that that thing looked like—"

"Nomu," Himiko grimaced and met eyes with Izuku. "It looked like Nomu from U.S.J. That was what you were thinking, right?"

She reached out her hand, and with a start, he realized he had been shaking. Had he really been so frightened? Something had just come over him, and he had acted instinctually when he saw that creature—like he had to get it away from Himiko at all costs.

"We're lucky it wasn't as strong as the one from back then," Izuku planted a foot on the edge of the train and looked to Gran Torino, "What should we do?"

The town was in chaos. Off in the distance, he could hear sirens, people screaming, and the sound of battle. He could see more Nomu in the distance.

Gran Torino looked down at the Nomu Izuku had incapacitated. "For now, you two should focus on helping with civilian rescue. I'll help handle whatever this is. You got it?"

Both Himiko and Izuku nodded in unison, "Yes, sir."

Gran Torino shot away from the train.

Izuku looked at Himiko, and she seemed to be thinking the same thing as him, "You want to make sure Mister Glasses is okay, right?"

He crouched down and let Himiko up onto his back, "I'm worried. The Hero Killer was spotted around Hosu a few days ago, so what if Iida uses this confusion to go looking for him? It might be nothing, but I think we should ask the hero he was interning with, Manual."

Izuku jumped from the train and along the tracks. One for All shot boots of static out from him as they zipped along and then jumped from rooftop to rooftop. The city square wasn't far, and it seemed to be where the most chaos was focused.

On the roof of a bank, Izuku and Himiko got a good look at the commotion. There, in the center of town, were two more Nomu. They were fighting a dozen or more heroes, and it seemed there was no rhyme or reason to their attacks; they were just lashing out indiscriminately.

Fires raged, civilians cried out in fear, and a few heroes even fell to the floor bleeding. Izuku couldn't tell if they were dead or just injured.

And through it all, he heard it.

"Tenya!"

Izuku looked down and found the man he had been looking for; it was the Normal Hero: Manual. But Iida was nowhere in sight, and even the pro hero seemed to be searching for him.

"Damnit! Himiko! I think Iida ran off already."

Himiko scanned the field and seemed to come to a conclusion, "if the Hero Killer is here, and Mister Glasses is after him, we'll need to find a place far away and removed from all of this. Stain never operates out in the open; we need to search nearby back alleys and hope we get lucky as we comb the area."

"Got it!" Izuku leaped from the roof of the bank and made a wide arc around the fight to start searching alleys.

'Please be okay, Iida!'

Stain glowered at the boy in front of him. Because that was exactly what he was: a boy.

He didn't know the first thing about truly being a hero, about duty, honor, or sacrifice. If he did, he wouldn't be trying to stop him from carrying out his work. And he wouldn't be foolish enough to be seeking vengeance for his false hero brother, Ingenium.

Sure, the man had seemed heroic on the surface, but dig even a little under the surface, and Stain had found his true nature. He was a vain and materialistic man unworthy of the title of hero.

And it seemed his brother was no better.

The boy charged at him, screaming in anger. Stain leaped over the upward kick the child had thrown and dug his metal spiked boot into the boy's shoulder.

"Ingenium's… brother? I used him to get the rumors going. But you. You're," blood splattered across Stain's boot, and he used the foothold his boot had made out of the boy's shoulder to slam the sole of his other boot into the back of the boy's head, "so weak!"

Stain drew his katana from its sheath and slammed the blade down into the hero-wannabe's shoulder, "Both you and your brother are weak! It's because you are posers."

"Shut up, evildoer!" Stain glared down at the boy and let him have his piece. After all, even fakes were allowed some last words, "the damage you did to his spinal cord means he's probably going to be crippled for the rest of his life! He'll never be a hero again! My brother… he saved so many people… he's a leader. He's a great hero! There's no good reason you could possibly have for crippling him!"

'How pathetic.'

The boy started to lift up along the sword that was pierced through his shoulder, "he's my hero… he's a great hero… who inspired my dreams! I'll kill you for what you did!"

Stain sneered down at him and pointed over to the fake hero he had been about to cull, "save him first. Forget about yourself for a second and try saving others. Don't wield your power for your own sake. Getting trapped by your own hate and acting out of self-interest… makes you the furthest thing from a hero."

He pulled the blade from the wannabe's back, drew it up to his cracked lips, and licked the blood. This was turning out to be a most bountiful harvest indeed; not only had he caught the fake hero, but he also had the chance to prune the weed that was sprouting in his carefully maintained garden.

He drew his sword up to cut the weed beneath his boot.

"Consider yourself a humble offering… to the betterment of society."

Tears welled in the boy's eyes, and he grit his teeth, "Shut up, shut up! IT DOESN'T MATTER WHAT YOU SAY NOW! YOU'RE STILL THE CRIMINAL THAT HURT MY BROTHER!"

The blade came down, but before he could kill the sniveling wretch, something small slammed into him. It planted two feet into his side, spun in the air, and threw two knives that narrowly missed Stain's chest and arm.

Before he could regain his footing, another object slammed into his face, "SMAAAAASH!" He was sent tumbling down the ally.

"M-Midoriya! Toga-San?!"

"We're here to save you, Iida!"

Stain looked up and saw two teenagers. One was a girl with blonde hair in an out-of-place elegant red dress. She wore gloves whose fingers were tipped with dangerous-looking claws and had knives all around her body, not unlike Stain himself.

The other was a boy a couple of inches taller than the girl. He looked small, but that hit had dislocated Stain's jaw. He had green hair, freckles, and a relatively plain costume with metal plates in various places that would guard vital areas.

'They look… familiar.'

"That piece of garbage and the society that worships him! I wanna turn them both to dust, but first, I want to corrupt those kids he seemed to care so much about and see the look of despair on his face as they rip his guts out."

'So these were the children Shigaraki was interested in,' Stain realigned his jaw, snapped it back into place, and readied the katana he had managed to hold onto, readying for a fight, 'if they aspire to be heroes, then I should test their metal, but if they fall short… let alone giving them to Shigaraki… I'll just kill them here and now.'

"Himiko knew a majority of the Hero Killers victims were discovered around blind corners in deserted areas… so we've been scouring the back alleys near the Normal Hero Agency, close to the center of all the trouble… looking for you!" The green one, Midoriya, pointed at Stain.

The girl, Himiko, looked down at Ingenium's brother, Iida. "Can you move, Mister Glasses? Izu might be strong, but we'll all need to work together if we want to survive fighting the Hero Killer."

The little hero wannabe grit his teeth, "I can't move… he cut me… that's likely his quirk."

"They were talking about that on the news," the green one shifted between Stain and the girl, "so he needs to cut you to get his quirk to work. I think we can deal with that. Right, Himiko?"

The girl padded over, her feet bare, and she drew a knife from a holster on her left forearm. "Oh yeah! We train in knife combat all the time, so we're a bad match for him."

The green one looked behind him and seemed to catch sight of the hero Stain had been moments away from culling, 'good spacial awareness, but this is the real test. What will you do, boy? Save your friend and run, or stay and fight to save everyone?'

"Midoriya, Toga! Don't interfere. This has nothing to do with either of you!" The brother of Ingenium grit his teeth and glared up at the two teens.

"Shut up!" The green one glared right back down at the other boy. If you're too stubborn to accept our help, then you don't have to! Just shut up, and let us save you both!"

"Your friend shows up and says, 'I'm here to save you,' and you have the nerve to deny his kindness? But either way, it's my duty to kill these two." Stain glowered down at the little hero wannabe and hooked a thumb over his shoulder at the man slumped against the wall behind him, "And if we're forced to fight, the naturally… the weaker of us will be culled."

Izuku shuddered. This man leaked malice by the gallon, and he looked just downright freaky. He didn't look like a heteromorphic type, so why was his nose so flat? And that stare… Izuku didn't want to admit it, but it leaked a certain horrific charisma like a twisted version of All Might's presence.

"So," just one word was enough to make Izuku's spine tingle and his knees to go weak, "what now?"

This was it. The moment that would make or break Izuku as a hero, but could he stand up to this monster? He was different compared to the guys at U.S.J. He was, for lack of a better word, more driven. There was real conviction in his eyes, even if it was twisted.

Out of the corner of his eye, Izuku could see Himiko shivering, but she shifted forward as if she were ready to spring and protect Izuku.

That broke him out of his indecision. If Himiko would fight, so would he!

Izuku crouched down into a runner's stance, tensing his leg muscles for a sideways jump toward the alley wall.

"No! I told you to run! This is none of your business!" Iida shouted, barely managing to shift even a millimeter as he did.

Izuku glared right back at the Hero Killer, "How are we supposed to leave after you say crap like that? Didn't you know?"

Himiko stepped up behind Izuku and flipped her knife in her hand, "Giving help even when it's not asked for…"

They both sprang into action, shouting in unison, "is what makes a true hero!"

The Hero Killer broke into a maniacal smile, his ghoulish face and matted hair adding to the grotesque look, "Ahhh! Good!"

Izuku watched as Stain readied his blade to cut Himiko's head off, but he wouldn't let him. Izuku's feet planted into the wall, and then he was shooting right for the Hero Killer.

"You're both trying to close the gap against my long blade… good judgment," he reached for a knife on a thigh holster.

'Think outside the box like Gran Torino said! What can I do? One for All enhances the muscles and nerves to superhuman levels, and my brain is a nerve, so maybe…'

It was difficult, but Izuku imagined the crackling electricity of One for All supercharging his brain.

His mind seemed to open up, like a sports car that had been trundling along on a rough road, and suddenly found its way onto the freeway. Everything seemed to slow down to a crawl; the Hero Killer's hand moved centimeter by centimeter for Izuku. Himiko's foot seemed to move through molasses as she was already preparing to dodge the katana swing he was aiming at her.

Izuku turned his attention from the blade near Himiko. She was skilled enough to evade without his help, so Izuku used One for All to allow his body to keep up with his thought processes. He brought his hand up. It felt like an eternity to him, but compared to the Hero Killer's movements, Izuku's hand would be up first.

Stain drew the knife out and threw it straight at Izuku, but he was prepared. Izuku's hand was already up; he spread his index and middle fingers and closed them like a steel trap around the knife. With his enhanced reflexes, Izuku flipped the knife in one fluid motion and threw the blade back at the Hero Killer's right arm, the one he held his sword with.

But Izuku wasn't done. He was still mid-jump and would collide with Stain if he didn't act, so he used the opportunity to ready a sideways kick at the man's temple.

His foot was just an inch from the man's head when the world returned to normal. Izuku's head throbbed, his vision swam, and he shot right past Stain and Himiko.

Izuku landed in a heap next to the pro hero Stain had been targeting originally, 'I don't think my brain can handle more than a couple seconds of the strain One for All puts on it.'

He looked up to see how the fight was going now that time had resumed, but everyone in the alley was staring at him in awe. Himiko had forgotten to follow up with an attack, and even the Hero Killer stared at Izuku in shock.

"Izu!? How did you do that? I never trained you to catch knives?!"

The Hero Killer glanced at Himiko momentarily and then back to Izuku. His shoulder was limp, and blood trickled from the knife that stuck in the joint, "you're better than I expected."

He pulled the knife out of his shoulder with his free hand and licked the blood from the blade," so many fools out there are nothing but talk, but you… are worth keeping alive."

"Now," he turned to Himiko and picked his katana up from the ground where it had fallen, "it's your turn to be tested!"

Izuku tried to fill himself with One for All, but he couldn't move, 'what!'

A slight twinge between Izuku's fingers alerted Izuku to a small cut he had gotten when catching the knife earlier, 'a cut that small can even paralyze you?! No, think about it! I could still move even after I'd cut myself, but I wasn't able to move after he licked the blade… blood!'

"It's blood! He needs to ingest blood like you for his quirk to activate, Himiko!" Izuku tried struggling to his feet, but no matter how hard he tried, his body wouldn't respond, and One for All just wouldn't activate.

Himiko and the Hero Killer clashed. Himiko's blades were far too small to challenge the much larger katana properly, but with the added handicap of Stain using his off-hand, she somehow avoided his blade with practiced ease.

"I always liked you, Stain, but you threw a knife at Izu! So I'm going to cut you," Himiko dodged under a vertical swing, leaped over the follow-up horizontal slash, pirouetted in the air, and launched three knives at the Hero Killer's legs and remaining arm.

He angled his shoulder away, avoiding the knife meant for his other arm, and swung his sword in one move to knock the knives meant for his legs away, "your accuracy is good, and you're agile, but you're certainly not very heroic. I can see why that man wants you, but I don't get what he saw in the boy. He's far too heroic to be consorting with filth like you and Shigaraki."

'S-Shigaraki?!' Izuku started to panic, 'no wonder there are more Nomu here! It's all because of Shigaraki. But does that mean the Hero Killer is working with him?'

He needed to break free of this paralysis soon. How did the Hero Killer's quirk work? Was it manual? Did he have to release them himself? Did the amount of blood he took in matter, or was it down to just getting any of the target's blood?

Himiko glared at Stain. Her usually feral grin was gone, and in its place was a predator's stare, "You aren't wrong. Izu is way too good for someone like me. He's kind, thoughtful, protective, and downright noble… but I love him, and he loves me. So I'm not going to leave him just because of some Teenage Mutant Ninja Turtle reject with a poor sense of fashion."

She threw another set of knives at him and charged forward.

The Hero Killer deflected the projectiles and then paired the blade Himiko had aimed at his leg joint; their blades locked together. Stain stepped to the side, throwing Himiko off balance. Then, he spun in place and swung his katana down in a decapitating swing, "You are an attachment that boy doesn't need. If you are near him, either he will succumb to the taint you are spreading to his soul, or Shigaraki will take you both and corrupt him by using you. Before that happens, I will set the boy free of you."

The katana was little more than a glint in the air as it swung down with tremendous force. Izuku could see the air parting around the blade, see Himiko's foot slip on a patch of water that she had stepped into, and see that she wouldn't be able to dodge because of the slight mistake.

His finger twitched.

"Now!" One for All lit up the alleyway, his muscles tensed, and Izuku could feel the restraint of eight percent being dialed up even further.

He shot forward and cleared the ten feet between himself, Himiko, and the Hero Killer in an instant.

His muscles had grown accustomed to eight percent, and now he was pushing them with the strain of ten. The speed differential seemed like night and day in this instant. The increase was negligible at best, but it had been the difference between life and death.

The flat of his foot slammed into Stain's chest. The sound of breaking bones echoed in the alley, and all Izuku could do was grin.

The Hero Killer tumbled away and slammed into a wall nearly thirty feet away. Izuku stumbled as he came to a stop next to his girlfriend. "Don't ever threaten Himiko in front of me! Or I'll kill you!"

Izuku could feel the burden of One for All at ten percent. It felt similar to eight percent, but his muscles seemed to have reinforced and grown as taught as a bow string. He felt like he could shoot off in any direction with great speed at the slightest twitch.

He stooped down to help Himiko up, and it was the most difficult thing he'd ever done. It was like the quick twitch muscles in his body were all dialed up to eleven, and he could snap at any moment.

Himiko grinned toothily at him, "Why, Izu, I never knew you cared so much."

Izuku held her hand in his with great care. Under the power of One for All, she felt lighter than air, and he barely registered the weight of her hand as he held it.

Somehow, Stain had managed to pull himself up to his feet. Whether it was through sheer willpower or just a stubborn unwillingness to go down, Izuku didn't know.

Stain stumbled forward, clutching his chest, "You've gotten faster and stronger, too. Were you holding your power back? No, judging by the way you were moving, you were just as taken off guard by your speed as I was."

Izuku glared, "And what about you? Your power barely even lasted that long on me. I have a few theories about your quirk. The others didn't break out of their paralysis, even though I did, so it's not that you lost focus. There can't be a time limit; otherwise, the others would've broken free before me. Most likely, it has to do with the amount of blood you ingest, the number of people you're using your quirk on, or it's down to the blood type of the affected victims."

The hero Stain had intended to kill grunted. Izuku recognized him as the hero Native, "If it's down to blood type, mine is B."

"Mine is type A," Iida tried to move again, but it seemed he was still under the Hero Killers quirk effect.

Izuku looked at Himiko, briefly nodding; he readied himself for another charge, "I'm type O."

"And I'm AB," Himiko drew more knives from her thigh holster and nodded back.

"Haaaaah," the Hero Killer exhaled heavily, picking up his dropped katana and readying himself for their charge, "you're sharp. That's right, my quirk's effectiveness depends on the blood type of my target, but that does you little good in a fight like this, where a moment can be the difference between life and death."

Himiko shifted toward Izuku and whispered, "he isn't wrong. The more drawn out this is, the greater our disadvantage will be. You can't handle One for All at that output for very long, and I can't fight without making a mistake forever."

Izuku pulled his phone from his utility belt and held it behind his back. He heard the light click as he unlocked the screen. He hoped he was scrolling to the proper screen.

He tapped on the phone several times and heard a *whoosh* come from his phone. Their location had been sent, and hopefully, someone in their class would understand his cryptic message. It wasn't a perfect backup plan, but it would be their final lifeline if they couldn't stop the Hero Killer soon.

"Throw me at him."

Before Izuku could fully register what she'd said, Himiko leaped into the air, and Izuku had readied himself as if he were bumping a volleyball. His muscles tensed, and Izuku sent Himiko rocketing toward Stain.

A/N: I don't know if using One for All to improve cognition really makes sense, but I always saw it as a quirk that enhances the muscles, reinforcing them with the energy the quirk generates. So, I didn't think it was too much of a stretch to say it could be used to speed up thought processes, too. After all, how could All Might possibly keep up with his own insane movements if it didn't also allow his brain to keep up?

I hope you enjoyed!!!!