So, uh… how we feeling in light of… recent developments? Don't mind me lol I'll just be over here *furiously scribbling shit in and out of the rough draft*
Also, I suppose there's some… suggestive stuff in this chapter. Just so you know.
"Guys, I'm sorry for all the trouble I caused!" Izuku declared intensely, bowing.
"No sweat Deku! Thanks for your hard work!" Ochako grinned.
"All he did was vacuum." Kyoka pointed out with a deadpan.
"Welcome back to the fold, Izuku!" Hitomi pumped an eager fist.
If only Katsuki was back too.
"Class rep, Iida! I'm sorry I disappointed you!" Izuku continued with high energy.
"Er— right! Well, I'm glad you learned from your mistakes. Follow the rules from now on."
"I'll catch up with everything I fell behind on these past three days!"
"That's the fightin' spirit! Do it, man!" Eijirou cheered him on.
"Time to take your seats, everyone." Mr. Aizawa appeared behind the freckled teen, looming threateningly.
They were all at their desks at record speed.
Hitomi shot a small frown at the empty one behind her.
"Morning. Now that Midoriya is back we'll go into more detail about what the work studies entail." He looked to the classroom door. "Go ahead and come in."
It slid open, and three older students entered.
Hitomi gasped softly, her face flaring upon seeing the one in front.
It was him. The blonde that saved her from falling all the way back before the USJ.
"I'll have people who've experienced them firsthand to explain. I suggest you listen carefully as they point out how work studies differ from internships. These three are third years at UA." Mr. Aizawa gestured to the students. "They rank at the very top of our student body. You may know them as The Big Three."
Along with the blonde there was a girl with periwinkle hair and eyes, who wore a cheery smile. And then there was another guy, who stood slightly slumped and defensive, with pointed ears, and black hair that he hid behind.
Hitomi blinked, realizing suddenly that she recognized him as the boy who retrieved the blonde after he caught her.
"The best of the Hero Course…" Sero whispered nervously.
"The Big Three." Eijirou parroted in awe.
"Oh, wow!" Mina bounced in her seat.
"Of all the talented students here, they're the ones at the top." Tenya summed up.
"They're on a different level. Still in school, but practically Pro Heroes." Momo marveled.
Hitomi finished her inspection of the other two, refocusing on the blonde. Only to see he was already looking at her with an expression of recognition.
He smiled wider.
Steam puffed from her scarlet face.
"Get to it. Introduce yourselves briefly." Mr. Aizawa prompted. "Let's start with Amajiki."
The blacked haired teen raised his head, his stare deep and brimming with intensity.
But he smelled overwhelmingly of anxiety.
After a tense second, he started to tremble.
"It's no good…" He croaked. "You two go. I just can't. Even if I try to imagine them as potatoes, I can see their human bodies. I know that they're still people… No words are coming out. My mind's blank and my mouth is dry. I can't say anything. I wanna…" he spun around and faced the wall. "…go home."
Aw. Hitomi almost cooed aloud. Poor guy.
"Okay… so, um, are you really one of UA's top Heroes?" Ojirou asked skeptically.
The periwinkle girl giggled. "Come on, Amajiki! You need to have the heart of a lion, not a kitten. You know, even though you're human. Get what I mean?" She turned back to face the class, gesturing to Amajiki. "This is our kitten, Tamaki Amajiki. And hi, my name is Nejire Hado. I'm supposed to talk about work studies. You first years have a really exciting time ahead of you." Hado blinked, approaching Mezou's desk. "Hey, wait, hold on. Why are you wearing a mask? Is it 'cause you're feeling sick? Or just… trying to look cool?"
Mezou leaned back away from her uncomfortably. "Uh, well—"
"Oh, whoa!" She shifted her sights on another person. "And you must be Todoroki, am I right? Yeah. How'd you get that big burn on your face?"
Shouto sat straighter. "That's none of your—"
"Saito, can you really smell like a dog can? What do I smell like? Oh, you have a scar too! How'd that happen?
Hitomi sat quietly with a blank face, giving no response, her ears flicking erratically.
"And Ashido, if your horns break off, you think you'll grow new ones? Oh, and can you wiggle them? Oh, Mineta, are those balls your hair, or what? I don't get it. Oh, oh, Asui! You're a tree frog, not a gross toad, right?" She bounced on her heels. "Oh my goodness! There's so much I want to know about every one of you! Let's have a Q and A!"
"Oh god, there's two of them." Sato muttered in horror.
Tokoyami shook his head in disagreement. "Saito isn't this tactless."
"Hey, Ojirou, can you support your entire body weight with that tail of yours?" Hado went right back to it.
"Uh, well, you see—
"Come on, tell me! I really wanna know!"
Mr. Aizawa's hair began to float, growing visibly irritated. "This is completely irrational."
The blonde spotted the teacher's mounting ire, and raised a placating hand. "Oh, there's no need for you to worry, Eraser Head." He pointed at himself with his thumb. "I'm up next, and I'll get the audience refocused!" He turned to them, taking Hado's place in the spotlight. "The future's gonna be…?!"
No one said anything, clueless as to what they were expected to say.
Hitomi would've said something, to not leave him hanging, if her mouth wasn't so dry.
"Gonna be what?" Denki asked after a long pause.
"Awful!" He chirped. "That's your part, guys! Oh crap, my call and response was a total fail!" Despite this, he sounded as pleased as ever, chuckling.
"Is it just me, or does it seem like each one of them is a complete weirdo? What's the deal?" Sato whispered to Kouji and Tokoyami.
"Their strangeness is palpable." The avian boy agreed.
The three boys suddenly stiffened, fearfully turning to look towards the murderous aura that appeared out of nowhere.
Hitomi sat almost backwards in her seat, expression shadowed, but eyes glowing furiously.
"Well I think he's endearing."
"Is it just me, or is she harnessing Bakugou right now?" Sato whispered with a gulp.
"Okay, you guys look like you have no idea what's going on." The blonde stopped laughing, growing more serious. "I guess we are third years who just showed up in your classroom to explain a program that's completely voluntary. I can see how you'd be confused by that." He put his hand to his chin. "Hm. You guys got your provisional licenses as first years, right? Huh! This batch of new students had proven to be pretty darn energetic. So the problem is… you must not have a sense of humor. That's why my joke didn't land."
Hado and Amajiki looked at him, the latter whispering a low "Don't do it."
The blonde thrusted a fist in the air. "Heads up, the rad new plan is all you first years fight me at once!"
"Huh? Huh!?"
"You wanna fight us?" Eijirou sputtered.
"What, like, now?" Sero arched a brow.
"Well, if you want them to experience our experience, this is a pretty rational way of doing it then." The blonde grinned at Mr. Aizawa. "Right, Eraser Head? Rational."
Mr. Aizawa sighed through his nose. "Do whatever you want."
"Yes!"
Hitomi was nervous to note that his scent held no sign of fear at all. He had no reservations about fighting them.
…
"Is he… for real?" Sero questioned lowly.
In Gym Gamma, the class watched as the blonde— Mirio Togata, stretched in preparation.
Togata heard him, and grinned. "Oh yeah. Totes real."
"Mirio, you're impossible." Amajiki sighed against the wall. "It would have been simple enough for us to just tell them this is what it's like, here's what we learned from it. Not everyone has your level of drive. Plus, think about how bad it'll look if some of them can't recover after fighting you. No one wants to spend the next few years in a hospital bed."
There was not a single sign of a lie, or deception in order to psych them out. His scent and his voice held true. He believed completely that Togata could destroy them thoroughly.
Togata could crush them— probably all with that charming grin on his face.
Hitomi shifted, face burning. Her lower stomach tightened in a foreign way, and her thighs pressed together.
What the…?
"Hey, listen up! It's story time." Hado started toying with Mina's horns. "Long ago, a student got frustrated in class and quit being a Hero, and it was terrible for everyone. Did you know that? So, Togata, I know our job is tough, but you better make sure you know what you're doing. Be careful, okay?"
"Please stop touching those…" Mina whimpered.
"Let's think about this. You're obviously much further ahead than us. But we've fought Pros before." Tokoyami pointed out.
"Not to mention, we took down some legitimate Villains." Eijirou smirked. "I don't think you need to worry about hurting us. We're not a buncha wannabes."
Togata nodded once. "Mm! Heard. But you're gonna have to show me that's the truth. Now, who's gonna start this party?"
God, he's so confident!
"I've got this!" Eijirou hardened his arms.
"No, I'm first." Izuku cut in.
Eijirou slumped. "You stole my thunder!"
"View this as a learning experience." Mr. Aizawa called to them. "It's a good opportunity for you."
Togata grinned wider. "Oh, the problem child! Yes, this is perfect. I've heard you got plenty-a fire in ya."
Izuku took a battle-ready stance.
"The close combat team should surround him first thing!" Sato suggested.
"Let's do it! We've got ourselves a new mentor. Thanks for the opportunity, man…"
Hitomi took a breath, focusing that tingling sensation into her hands, watching with proud satisfaction as her hands grew slightly, claws extending.
Still not as big as they were before— but still good.
"The opportunity to kick your butt!" Eijirou finished smugly.
Izuku launched forward.
Togata didn't move, but— but his clothes—
Kyoka screamed, slapping her hands over Hitomi's eyes.
But it was already too late.
The pinkette's whole body seared scarlet, puffing out steam as incoherent babbles fell from her mouth.
That tightness in her stomach turned into a pull, and a burning heat spread down between her—
"Her innocence!" Sero covered Kyoka's hands with his own.
Mina cackled once, upon seeing the two trying hysterically to salvage her purity.
"Oopsie! My Quirk's kinda tricky." Togata sheepishly chuckled.
There were some sounds of shoes skidding on the floor, then Togata spoke again, amused.
"Went for the face, huh?"
"We have to avenge our pure sweet Hitomi!" Sero cried, shooting tape.
Kyoka let her go finally, and when Hitomi opened her eyes (a little too eagerly) she saw Togata had put his pants back on.
Oh, and every attack was phasing right through him.
…Wait—
A mass attack failed, and when the smoke cleared, he was gone. Only to burst from the ground right behind Kyoka.
Hitomi squeaked, because his pants were gone again—
"I think I'll start by taking out the long-distance fighters!"
Kyoka screamed, flushing not nearly as strong as Hitomi did.
"He warped?" Mezou gasped.
"His power isn't just slipping through things?" Sato surmised.
"How'd he luck out with such a good Quirk?" Eijirou asked in offense.
Hitomi paused, something clicking.
He phases through… he came from the ground…
Hitomi's head shot up. "It's not warping! He's falling through—"
"Sorry but—"
A horribly strong punch landed right in her stomach, sending her stumbling back.
"No spoilers!" Togata chirped at her, as if he hadn't just given her internal bruising.
But what he wasn't expecting was for her to be made out of denser stuff than he thought. After all, that punch was nothing compared to a kick from Aunt Rumi.
After only a second to regain her breath, Hitomi surged forward, claws growing.
Togata actually grinned at seeing her still standing.
She took a swipe— then another, both slipping right through him. She growled, feeling strangely desperate to land a hit, and prove herself to him. The feeling was familiar, but in the moment she couldn't place why.
"Sorry about this."
Togata reared back a punch, and Hitomi raised her arms, crossing them in a block in front of her face. She widened her stance, preparing for the brunt of it— just how Aunt Rumi trained her.
But his fist phased through her arms, before striking her in the chin.
Hitomi grunted, eyes scrunching shut as she saw stars. Her back hit the floor, and she tasted blood as it filled her mouth.
Yeah… that was a solid hit.
More of her classmates weren't far behind.
"Power!" Togata roared after whipping out half of them like it was nothing. "I think that's it for the long-distance fighters."
And Hitomi.
"All that's left are the ones who specialize in close-quarters combat."
Nope. No. She refused to throw in the towel already after two measly hits.
She groaned, rolling into her front, and getting to her knees. Ochako distractedly gave her a hand up, never taking her eyes off of Togata.
"I have no idea how he just did that." Eijirou admitted.
"It's one thing to be able to phase through stuff, but warping too?" Ochako frowned anxiously.
"He's unrivaled." Ojirou grimly observed. "Do we stand a chance?"
Togata— with his pants on again, took a prepared stance. "Hold the flattery."
Oh, but I've got plenty.
Hitomi shook her head, wondering where that thought came from, and why it almost sounded like Aunt Nemuri.
"There's more to his Quirk than we're seeing!" Izuku warned. "Whether his true power is slipping through matter, or whether he's somehow warping himself through space… Either way, he's still landing his attacks directly. We should be able to counter him in the moment he's about to make contact. Even if we can't tell what he's doing, we should theorize with what we do know, and use that knowledge to find a way to beat him."
Hitomi opened her mouth, then hesitated.
"No spoilers!"
"Yeah, you said it! House arrest didn't put a dent in your fightin' spirit!" Eijirou praised.
"Then see if you can figure out how to win!" Togata charged at them, then fell through the floor, leaving behind his pants.
"I knew it!" Hitomi pointed damningly at where he disappeared.
Togata jumped up through the ground behind Izuku, who was already turning and kicking.
But his foot just passed through Togata, who grinned.
"Watch this! An ultimate move! Blinder Touch Eyeball Crush!"
He jabbed Izuku in the eye, phasing through for the most part, then punched him in the stomach.
"I've discovered that most people try to launch a counter-attack just like you did. So naturally I've trained to work around such moves. Nice try, though!" He disappeared into the floor again.
Hitomi knew what was coming next— could sense it. So in split-decision, she closed her eyes and focused.
The air behind her was displaced.
Hitomi dropped, and his fist went sailing over her head by mere centimeters.
"Man, you don't like to stay down!"
She pivoted in a crouch, opening her eyes as she snapped out her right fist.
It phased through his stomach.
Damnit!
"Close, but no cigar!" Togata took a fistful of her hair, jerking her forward and kneeing her in the stomach.
Hitomi gagged, coughing and choking on air. When he let her go, she dropped to the floor, curling up and cradling where he hit. It was much harder than his previous punch there, and left her winded and close to losing her breakfast.
A round of strikes and grunts, and in seconds the last of the class was on the ground, writhing in pain.
"Power!"
It really was.
…
"I tried to make it so you wouldn't see my willy. Sorry if you got a peek."
I'm not.
…Should she be concerned about herself?
"But anyway, that's a taste of what it's like to fight me." Togata grinned merrily.
"We all just got punched in the stomach without ever knowing what was going on." Izuku whined.
"Right, so, whaddaya think? Isn't my Quirk strong?"
Hitomi blinked, ear twitching. There was something in his tone… something sly.
"Yeah, it's too strong!" Hanta raged.
"How can you slip through things and warp? Do you have two powers like Todoroki does?" Mina joined in.
"Nope. Just the one."
"Don't you guys get it? I mean, you saw him doing it?" Hitomi cocked her head at her classmates.
"What are you talking about?" Kyoka crossed her arms.
"Oh! I know! I'll tell you what his Quirk is!" Hado looked at Togata, then back at them. "Hey, hey, can I say it? Permeation! Cool, right?"
"Hado, let Mirio explain his own power." Amajiki somberly chastised.
"Yup! I've got a sweet Quirk that's called Permeation. What you guys thought of as a warp was simply an alternative application of that power. Saito's the first one to figure it out, nice work!"
Hitomi flushed under the praise, shuffling her feet.
"Hitomi noticed it before you, Midoriya?" Denki teased.
But Izuku was enthralled by the new discovery. "So, how exactly do you warp, huh?"
"I activate my Quirk in my entire body. Then, I can pass through anything I want, no sweat. Everything! That includes solid ground."
Ochako gasped. "Oh, so that was you falling through the floor of the gym?"
"That's right. I went deep underground. And then, whenever I release my Quirk while I'm falling, something super strange happens. Apparently things with mass can't overlap. That's called physics!" Togata explained with a chuckle. "So, I get repelled upward! Think of it this way. The ground spits me out, and I fly up into the air. That's how my warp works. By adjusting the direction I'm facing or the pose I'm holding, I can change the angle I come out at, so I can aim at different spots."
"That sounds like a buggy video game." Mina pouted.
Togata cackled. "Hey, that's pretty funny!"
"You're able to avoid any attacks. And you can move where you want in an instant. Wow, you were born with a really strong Quirk." Tsuyu appraised.
"Not true." Togata's voice turned more serious, despite his smile staying the same. "My power's only strong because I made it that way. While my Quirk is activated my lungs can't take in oxygen. Even if I breathe in, the air'll just pass through. In the same way, my eardrums don't work. And light can't go through my retinas."
Hitomi clenched her fists.
It sounded like a nightmare. And yet he did it all with a smile.
She found herself amazed by Mirio Togata.
"I can pass through everything. But that means I can't feel anything when I'm in that state. Even though I have a body, I can't stop falling. I could probably keep going down forever. Does that make sense? That's why, if I wanna go through something like, say, a wall, I have to concentrate really hard. I'll activate everything except one leg. Then I release the other leg and land on it. And then the first leg is the last one to go through. Even for a simple action like that, there are a bunch of little steps involved."
"Oh man, if I were in a hurry I would mess that up every single time." Denki commented.
"Seriously, if you can't feel anything, how are you supposed to move?" Mineta wondered.
"Growing up, I was always behind, as you might expect. In no time, I'd dropped to dead-last. I dropped my pants a lot, too." Togata raised his left arm that was littered with scars. "In order to get to the top with this Quirk, I couldn't just hope that things would get better. I had to think." He tapped his forehead repeatedly. "I learned to make combat decisions. And picked up a few new tricks. But above all, I learned to predict what would happen next. And what made those predictions possible in the first place was experience. I based my predictions on what I'd learned. This was kind of a roundabout way to get the point across, but that's why I wanted to fight. To show you through experience rather than words. In our work studies, we're not treated as guests like in our internships. We're regarded as one of the Sidekicks, or even as a Pro! That can be super scary. Pros can get hurt. And sometimes they end up watching people die. But every scary and painful thing you go through is an important experience that you can't get inside a classroom, even at UA." He clenched a fist. "I transformed the experience I got in my work study into power. That's how I got to the top spot! And it's why I think they're worth it, even if you're scared. Ya with me, first years?!"
Hitomi swallowed, standing tall and nodding firmly.
"Yeah!"
…
"Hey! If you've got trash then bring it over here, right now!" Katsuki demanded soon after they all made it back to the dorm.
"Bakugou, thanks!" Eijirou brought a bag over.
"Sure!"
"I have some as well." Tokoyami carried his own.
"Hand it over!"
"Mine too!" Denki smirked.
"And mine." Hanta added on.
"This is heavy." Mineta laughed as he lugged a bag twice his size.
As more and more of the boys dumped their trash off on Katsuki, the blonde trembled with rage.
"You bastards! It's like you've been hoarding this for weeks!"
Hitomi sat on the couch, along with the rest of the girls. She rested her chin on her palm, staring into space with hooded eyes and pink cheeks.
Now that things had calmed down, everything was catching up to her. Everything she saw.
There was a tap on her shoulder, and she yelped.
"There she is." Mina teased. "What's on your mind?"
"I, uh…" She smiled softly, toying with her hair. "I was just thinking about… how amazing he was." She breathed the latter half, not bothering to hide her dreamy tone.
There was a sharp spike of burnt caramel.
Mina blinked at her, then squealed.
"Oh my god! Oh my god! You like him!"
There was a small crackle and pop.
Hitomi stiffened, reeling back and flushing now in embarrassment.
"No way, really?" Ochako's eyes widened.
"I—"
"What?! Him?!" Kyoka gawked in outrage.
Mina rolled her eyes. "Come on, Jirou, what happened wasn't that bad! In fact, we should be marking our calendars. Today we made history!"
"Yeah? Did Deku break his legs this time?" Katsuki sarcastically interjected as he passed them, his voice oddly strained.
Over where he stood, Izuku gave a minuscule pout. Katsuki knew very well that he'd broken his legs before.
Mina smirked mischievously, standing and approaching the blonde. "Nope. Today, Hitomi saw a handsome boy's junk."
…
Simultaneously, Hitomi's face bloomed red, and Kachan's palms exploded in involuntary sparks, melting the garbage bag handles. His back went ramrod straight, and when he turned to Hitomi, he was snarling.
She must have mistook the expression for one of judgement, quickly waving her hands in denial.
"It's not like that! I wasn't an active participant or anything! H-he just dropped his pants in front of me!"
Oh god.
"What?!"
While Kirishima and Hitomi rushed to try to explain what happened— unsuccessfully, due to Kachan's intense and stubborn ire —Uraraka came up to Izuku's side.
"It's kinda weird." She whispered in his ear.
Trying not to obviously shiver, Izuku pursed a smile. "W-what is?"
"Well, it kinda seems like Bakugou's being—"
"Katsuki, calm down!"
"Like fuck I'll calm down!"
"—Protective." She finished softly.
Izuku blinked, watching the scene closer. Never had he heard Kachan be described as protective. Surely this was just because of his excess irritation over being left out of a training exercise.
"It really wasn't like that!" Hitomi continued to appeal.
Ashido apparently wasn't done, saddling up next to Kachan— who was being restrained by a hardened Kirishima.
"I dunno. He was still naked when he went up and pulled you closer by your hair."
Kachan twitched.
Oh no.
"Name." He growled venomously.
Kirishima tensed nervously. "Come on, man—"
"Give me his fucking name."
He wasn't even yelling, and that somehow made it scarier.
Ashido cheerfully raised her hand. "Mirio Togata, in Class 3-A!"
Kachan started trudging on again, snapping threats at anyone in his way, but the words were indiscernible along with Kirishima's failed reasoning, Hitomi's desperate excuses, and Ashido's pleased cackling.
"Sero, help!" Kirishima cried, getting his friend to aid him by holding back Kachan with tape.
Hitomi stood in front of him, hands out in a placating pose.
"Denki, door!"
Kaminari ran to stand in front of the door, as the last line of defense. A very reluctant, and scared line of defense.
"Sparky if you don't move I'll fucking kill you!"
"Denki don't you dare!"
Kaminari grimaced, fidgeting anxiously as Kachan slowly but steadily made his way closer. "Shit. Shit. Shit."
"Perhaps we should get a teacher." Iida now stood on Izuku's other side. "I've never seen Bakugou so…"
"Protective!" Uraraka gave a shouted whisper.
Iida pushed up his glasses. "Yes, actually, I suppose that's exactly what it is."
Izuku watched on, conflicted between being worried for Togata, amused by the whole situation, or…
Or stunned, by the care Kachan didn't seem aware that he was showing.
…
By the time dinner rolled around, Katsuki had been talked down, despite his best efforts.
That didn't mean he was happy about what happened. Oh fuck no. He made it his decision then and there that he would someday pummel the bastard, if it was the last thing he did.
(The source of his motivation for doing such, and the cause for his anger about the whole situation, were staunchly stomped down and ignored.)
"Hey, Kachan?"
Great. Just what he needs.
"What?! I swear if you say a damn thing about how class was today—"
"You were right."
Katsuki faltered, brows furrowing. "Hah?"
Deku turned his head, looking over at where Saito was focused intently on destroying Kaminari in Fatal Combat over in the TV area.
"She is a lot smarter than we give her credit for. I see that now."
The damned nerd started to smile— a soft and fond one.
Katsuki scowled, fresh fire pooling in his chest. "What, you like her or something?" He scoffed scathingly.
"What?! No way!" He floundered, whisper-shouting in a panic. "I-I mean, not that there's anything wrong with her! She's nice, and really pretty—"
Katsuki's palm sparked.
"But no! I don't like her like that!" Deku deflated, then studied him closely.
Katsuki snarled. "What?"
Deku was unfazed, his expression torn between hope and disbelief. "It's just… I can't tell if what I think is happening, is happening. I mean, it's never happened before. But now… It might be happening."
He was seriously gonna hit him. Extra punishment be damned.
"The hell are you talking about, nerd?"
Deku shook his head, having the gall to smirk faintly.
"Nothing. You'll figure it out. If you haven't already."
Katsuki gritted his teeth, hands opening and closing with the desire to blast the loser in the face.
(Because there may have been a small part of him that knew exactly what Deku was talking about. And the last thing he needed was for it to be addressed.)
He let his eyes fall back on her, noticing— despite himself —that she was once again wearing that old blue UA hoodie. The one she always wore after a tough day of training. The one that made her look—
The sound of the narrator announcing Kaminari's failure broke his gaze, carmine eyes darting away before she looked away from the screen.
"Katsuki Bakugou is going to become the most amazing Hero the world has ever seen!"
"I was just thinking about… how amazing he was."
Katsuki clicked his tongue, stalking off with a sourness lingering on the back of his tongue.
Part of me worries about making Hitomi OP and like a Mary-sue, but at the same time, she can't stay stagnant in her skills, she has to get better and stronger with the rest of the cast. As for stuff like her being able to "sense" things coming, it's another of her canine abilities. Not many people know, but dogs actually have whiskers like cats do, that they use to pick up on small changes and incoming threats.
Someone pointed out that no one can actually see the sparks around Midoriya when he uses his Quirk, and my explanation for Hitomi being able to see it, is because dogs actually can see electromagnetic stuff like that (yeah she was able to see it in a recording of him too, even though that shouldn't be possible but shush)
And to address one last thing real quick; Katsuki is in a strange sorta limbo. If given the opportunity right now, at the current point in time, he would not be with Hitomi, romantically.
But he's also ready to murder anyone else that comes along, who might.
It's this sorta childish standpoint, where he's not ready— emotionally —to be with her. He doesn't want to make room in his plans for the future for her to fit in it. But no one else is allowed to have her. Full-stop.
He's being entirely selfish and juvenile with his feelings right now, as if she was a possession. He wants to put her up on a shelf, out of reach of anyone who actually wants to play with her, just so they can't (and so he always has the option to.)
So, to put it simply, Katsuki isn't ready for her, but no one else is allowed to swoop in and take her.