Ren's new martial arts instructor looked him up and down. Her cool grey eyes scrutinised every scar on his pale body as he stood shirtless in the Yaoyorozu estate's private dojo.

"Hmm. I can work with this." Kagami tapped her chin in thought. "You've been following the diet outlined by your nutritionist, right?"

"It included a lot of fish, so I had no problems with it." Ren's black cat tail quivered in joy upon remembering the delicious baked salmon he had for breakfast that morning. "Can I start my martial arts training now?"

"Yes, but first we have to decide on what fighting style you should learn," said Kagami "You can put your shirt back on now."

"I don't have any particular preferences." Ren slid on the top of his black gi. "Why don't you just teach me whatever yours is?"

"Kid, if I tried to teach you all the styles I know, we'd be here forever." She pointed a confident thumb at herself with a smile on her pretty face. "My quirk is called 'Mastery'. By watching martial arts masters at work, I can imprint their muscle memory onto myself and gain all their skills."

"That sounds like cheating," Ren said bluntly.

"More so than the ability to defy the laws of space-time?"

"Hmph. Touche." Ren stretched his limbs and let out a stifled yawn. "By the way, is it true that you used to teach the princess?"

"You mean Momo?" asked Kagami. "Yes, I taught her bojutsu and a bit of hand to hand."

"I see. On an unrelated note, what martial art would you recommend for beating up a bojutsu practitioner?"

Kagami let out a small laugh.

"The martial art itself matters less than the one who masters it," she assured him. "There can be many different styles and variations even within the same discipline."

"How do you suggest we decide on my style then?" Ren asked. "Try to teach me multiple styles and see which one sticks the best?"

The corners of Kagami's lips pulled up into a grin.

"Not a bad idea, but I have a better one." She placed a hand on her hips and looked down at Ren, towering at least thirty centimetres over him. "Fight me."

Ren blinked at her. The pupils of his coppery orange eyes dilated into slits.

"Excuse me?"

"Fight me," Kagami repeated. "No hold bars. Pretend I'm a villain coming at your new parents and try to take me down."

After taking a few seconds to process the request, Ren shrugged.

"Well, I'm down to throw hands but what exactly do you hope to accomplish by this?"

"It'll allow me to recognise your strengths and weaknesses first hand so I can pick a style that'll fit you," Kagami explained. "You can learn a lot about a person by fighting them, but you probably know that."

"I didn't learn shit from fighting the princess," said Ren dryly. "Except that crotch kicks are just as effective on women as they are on men."

"That just means you have plenty of room to learn!" Kagami raised her hands in a defensive position, her legs spreading out in a low fighting stance. "I'm ready whenever, Ren."

"Sure, sure, I just gotta get the rules down first," said Ren.

"I told you, there are no rules," said Kagami. "Pretend like this is a real fight."

"Like a street fight?"

"Exactly."

"So no rules whatsoever?"

"No rules whatsoever," Kagami confirmed. "Don't worry about hurting me. I can take-"

She was cut off when Ren suddenly kicked her hard between the legs.

Kagami's eyes nearly flew from its sockets. A breathless wheeze flew from her mouth as sharp pain tore through her nethers.

Before she could regain her bearings, Ren grabbed her by the sides of her head with clawed hands and sent a flying knee into her face.

Kagami stumbled backwards. A warm liquid trickled down her forehead and into her eyes, tinting her vision red.

'Did he cut me just now?'

She was barely able to finish the thought before she glimpsed Ren sliding past her between her legs to deliver a punch to her crotch, followed by a sweep kick that knocked her onto the ground.

Kagami felt her shoulder crash against the tatami mat hard enough to nearly dislocate it. A flurry of stomps to the face shook her brain inside her skull as her head was ping-ponged between the floor and Ren's bare foot.

Once she regained her bearings, Kagami caught Ren's foot before it could hit her face another time and threw it up with all her strength.

Ren rolled with the throw, backflipping off Kagami's hand before landing on all fours and charging at her again just as she managed to stand up again.

'Housecat my arse, this kid's a panther!' Kagami thought to herself as Ren threw a wild storm of kicks and punches at unpredictable angles. Her superhuman eyes barely kept up with the relentless assault through the pounding headache and blood obscuring her vision.

Over the course of two odd decades, Kagami had watched and fought with countless master martial artists, but Ren was a different beast entirely.

He had no particular style to speak of. Nothing to analyse or come up with a strategic counter for. Just pure unpredictability made all the more pronounced by the inhuman agility given to him by his feline quirk.

Every few seconds he'd switch from boxing on two feet like a brawler in a street fight to skittering on all fours with slashing claws.

Once Ren realised that she was worse at defending against the latter, he went all in on it, slashing at her joints and face with his claws.

Kagami was blinded by blood in her eyes, covered in cuts strategically placed to hurt her joints, and didn't have a second to think as blow after blow rained down on her. The effectiveness of her human martial arts were hampered against an opponent who seemed to have little interest in being neither human nor a martial artist. Only muscle memory and sheer grit earned through years of fighting kept her from being overwhelmed.

On one reckless lunge, Ren was caught off guard when Kagami grabbed him from the air and pinned him to the ground in a rear naked chokehold. He struggled for a bit before biting into Kagami's arm hard enough for his sharp feline fangs to draw blood.

Kagami winced in pain but refused to let go. Her eyes were still partially blind from the blood trickling into them from the cuts Ren made on her forehead. It would be difficult to get another chance to keep him down like this, and she wasn't going to waste it.

Ren then promptly vanished from her hold in a puff of black mist, having tethered himself to her gi during their grapple.

'Oh,' Kagami thought to herself, realising she messed up. 'I forgot he could do that.'

A flying drop kick hit her in the back, causing her to stumble forward. She turned around, her arms already guarding her head to protect it from another blow.

But instead of striking her head, Ren charged at her on all fours from below, headbutting her in the stomach in an attempt to tackle her to the ground. When she resisted, Ren stomped on her foot, holding her in place while he threw an uppercut to her chin.

Kagami felt like she was being nearly torn in two between her pinned foot and uppercutted head. The excruciating pain racking her body was only surpassed by how genuinely impressed she was.

'No doubt about it,' she thought to herself as she threw punches back at Ren, who managed to dodge or teleport away from almost all of them with uncanny agility. 'This kid's a prodigy.'

Kagami adjusted her strategy, falling into the defensive and trying to gauge Ren's attacks as best she could from the sound of his movements and the movement of the air around her.

'He came up with a strategy to counter me on the fly. Take me by surprise then blind me with my own blood so I can't properly read him with my quirk. Then to make things worse, he adjusts his fighting style to an animalistic one so I can't fall back on my martial arts instincts.'

Kagami grabbed Ren by the collar of his gi and threw him at a wall.

'The mind of a genius and the intuition of a wild beast. As far as martial arts senses go, he's the ideal!'

Ren planted his feet against the wall and used it to launch himself at Kagami, claws drawn and feline fangs snarling like a rabid animal.

'But even so…'

Kagami returned Ren's wall lunge with a charge of her own. At the very last second Kagami weaved to one side away from Ren's trajectory and clotheslined him hard in the chest, knocking the air out of her lungs and pinning him to the ground.

'No amount of talent beats experience.'

Ren laid on the ground, spent and panting from the blow to his chest. His body remained still aside from the rapid rising and falling of his chest.

"Let's take a little break," said Kagami in between pants.

She was just as tired as Ren was and a dozen times more injured. And yet, she was smiling. After years of being the best martial artist around, it was a little refreshing to almost get her shit rocked, even if she could've done without the crotch shots.

"Yeah, that sounds good," said Ren, half groaning in pain and exhaustion.

Minutes later, Ren and Kagami were in the mansion dining room licking their wounds. A first aid kit was on the table, which Kagami used to disinfect and wrap up the various cuts and bite marks Ren had inflicted on her.

Meanwhile Ren sat enjoying a healthy smoothie made for him by the family butler. His cat tail flicked side to side in contentment under him.

"You did pretty well," Kagami said in the understatement of the century as she finally patched up the cuts above her forehead. "But you have some points that could need improving."

"I'm all ears," said Ren through the smoothie straw in his mouth.

"For starters, you could learn how to conserve your energy better." Kagami plopped back a dislocated finger, then opened and closed her hand to test it. "You're fast, but you're not all that much stronger than a kid your age."

"My claws make up for it." Ren flicked on his retractable claws with a smug grin on his face.

"Your claws help, but you shouldn't rely on them," said Kagami. "Most of your attacks are far too wild. While a certain degree of wildness can make you unpredictable to the opponent, veer too much into it and you'll just be wasting precious stamina on unnecessary strikes."

"I know how to target my hits."

"Yeah, I figured." Kagami still felt an ache in her crotch where Ren had hit her multiple times. "But the majority of your attacks are still wild with only a few targeted strikes interspersed between them. You need to cut the wild strikes way down and learn to hit where it hurts instead."

"Like the crotch?"

"Aside from the crotch," said Kagami. "Pretty sure you already have that technique down pat."

"In my defence, there are very few fights that can't be won or at least significantly tipped in my favour by a good crotch shot," said Ren. "If I was ever caught back when I was a thief, I'd often just kick whoever caught me in the crotch and run away. Worked out just fine for me until I met the princess."

"It won't work on villains either," Kagami warned. "You need to change your mindset from a thief to a hero. Fighting isn't just a way to distract your mark so you can run away anymore. You have to learn how to take a person down and subdue them so that those around them are safe."

"Hmph." Ren sucked in a mouthful of smoothie and leaned back on his chair. "So have you decided on what martial art to teach me yet?"

"Kali, no doubt about it. The discipline largely focuses on weapons training. Your agility and almost disturbing lack of hesitation to hurt people makes you perfect for it-no offence."

Ren shrugged. "None taken, but shouldn't I also know how to fight barehanded too?"

"We can supplement it with muay thai for empty hand training," Kagami assured him. "Maybe some judo and wrestling for throws and grapples to cover all our bases."

"Did you teach the princess this many martial arts when you trained her?"

"No, for her it was mainly bojutsu and a little bit of karate." Kagami finished wrapping up the last of her wounds. "She's a brilliant, hard-working girl, but to be brutally honest, hand-to-hand combat just ain't her forte. Knowing just enough to get by is fine for her so she can focus on other areas. Her true potential lies in being a support hero with her quirk."

"Where do you think my potential lies then?" Ren asked.

"Combat and recon, no questions asked," said Kagami. "Your quirk is useful for both stealth and fighting. I can help train you in the latter but you'll have to figure out the stealth bit yourself."

"Eh, I'll be fine," said Ren. "I spent most of my life sneaking to places I shouldn't be."

"That doesn't mean you can slouch on your training," Kagami warned. "Experienced or not, you still have a long way to go, and you'll get sloppy if you don't train. Even the finest sword plunged into salt water will eventually rust."

"Yeah, yeah, no need to quote Sun Tzu to me," said Ren. "Don't worry, I'll figure out the ninja stealth shit on my own."

Kagami let out a soft chuckle.

"You're full of surprises, aren't you, kid?"

"It's best to always mystify, mislead, and surprise the enemy if possible," said Ren, throwing back an abridged quote of his own. "And as far as I'm concerned, anyone who isn't me is an enemy."

"That's a bit depressing," said Kagami. "Do you really think that?"

"I do," said Ren before stopping himself. "Well, used to anyways. I'm still not sure how much I trust the princess and her parents but they seem like decent enough folks. Which is surprising considering how rich they are."

"They're good people," said Kagami. "You can trust them."

"If you say so," said Ren, though he didn't sound all too convinced.

Kagami only left late in the afternoon. Mr and Mrs Yaoyorozu saw her off, trying their best to hide their surprise at how battered she was.

"How did Ren do?" Mrs Yaoyorozu looked concerned with how bloody Kagami was.

"He wasn't too much trouble, was he?" Mr Yoyorozu asked.

"Ah, it's nothing I couldn't handle," said Kagami with a bloody-gummed smile. "The kid's just full of potential! I daresay he's in my top five students of all time."

"Is there anything we can do to help with his training?"

"No, you two just leave his martial arts training to me." Kagami's expression softened along with her voice. "But, if you don't mind the suggestion, it might be good if you both spent some time bonding with him every now and then."

"I mean, it's not like I don't want to do that," said Mrs Yaoyorozu. "But we also want to respect his privacy, you know?"

Mr Yaoyorozu nodded in agreement. "The boy's been through a lot already. We don't want to put too much pressure on him."

"I understand that," said Kagami. "Just keep it in mind, alright? Something tells me that the kid's scars run deeper than his skin."

"We will," Mrs Yaoyorozu assured her. "See you next week, Kagami-sensei. And thank you again."

Kagami left the house with her mind running through lesson plans for her most promising pupil yet.

Said pupil, for his part, spent most of the day after training locked inside his room.

At one point, several of the household staff spotted Ren walking to his room holding plastic bags full of God knows what, having apparently left the mansion in secret to buy them with his hefty allowance. None of them spoke to anyone about it, deciding that whatever it was was probably his own business that they were better off not knowing.

When day turned to night, Mrs Yaoyorozu had Momo bring Ren down from his room to have dinner with the family.

Momo knocked on the door to Ren's room a little louder than what was necessary in case he was having another cat nap.

"Hey, Ren!" she called out to him. "It's time for dinner! Come out!"

"In a moment!" shouted Ren from inside the room.

There was a metallic cranking sound, followed by something like crackling electricity.

Curious, Momo tried to open the door. When it turned out to be locked, she used her quirk to make a key to open it anyways.

"What are you-" The last got stuck in Momo's throat when she saw the room.

Random junk and paper drawings filled the study desk, where Ren was hunched over something she couldn't see.

"Nosy bugger," Ren muttered to himself as he continued working on whatever it was he was so focused on.

"Ren, what is all this?" Momo walked over to Ren and looked over his shoulder. "Is…is that a socket wrench attached to a battery?"

"It's a homemade taser." Ren held up the long socket wrench, which had insulated tape wrapped all around the handle and a switch torn from an electric torch. He flicked the switch and the battery crammed in the socket lit up with crackling blue electricity.

"...Ren, why are you making a homemade taser?" asked Momo.

"Well, I'm going to need hero equipment when I get into UA." Ren turned off the pipe taser and set it aside. "Kagami-sensei's been teaching me kali stick fighting. I thought a stick with a built-in taser for extra oomph would help give me an edge."

"It's a bit jury rigged though, ain't it?"

Ren shrugged.

"I had a more complex design but it wasn't practical to make." He reached into a huge pile of sketchy blueprints and handed one to Momo.

"Hmm." Momo studied the highly complicated and meticulously detailed blueprint for a high tech taser baton up and down. "This…is a really solid design. I could see this actually working. It's actually kind of impressive."

"Yeah, but it'd be way too hard to make," said Ren before turning his attention back to his work desk. "I have some other equipment in mind too, like smoke bombs, specialised shurikens, a grapple gun…"

"...Ren," said Momo dryly with a deadpan look on her face.

"Well, the grapple gun might be a bit redundant since I can teleport but it won't hurt to have one around just in case. I can use some super pressurised gas cans to power it."

"Ren," Momo repeated, louder this time.

"I've also begun working on sketches for a mask," said Ren, clearly getting carried away showing off how smart he was. "I'll probably use a cheap festival mask or something as a base then combine it with a high-grade dust mask and charcoal. It should be a decent enough gas mask so I don't choke on my own smoke bombs."

"REN."

"The smoke bombs themselves should be pretty easy to make," Ren continued. "I'll just need some ping-pong balls, tin foil, and a bit of potassium-"

"REN!" Momo spun Ren around on his swivel chair to face her.

She looked him straight in his coppery orange eyes and held her hand up to his face. Glowing pink and blue matter shot from her palm. It materialised into a prototype of the taser baton shown on Ren's blueprint, perfectly replicated down to the listed sizes and dimensions.

Ren started at the prototype, then at Momo.

Momo placed the black polymer baton on his lap. He picked it up and flicked on the switch, causing its weighted tip to crackle with bright blue electricity much more powerful than the pipe attached to a battery on his desk.

"...Oh." Ren took a moment to just stare at his new weapon. "I forgot you could do that."

Silence fell between the two, which was only broken by the sound of Mrs Yaoyorozu calling for them to come down for dinner.