"Welcome to our home, Yuki! Please make yourself comfortable and join us at the table. We'll be having tempura!" Inko Midoriya said warmly, as she ushered Yuki Haro, (secretly the infamous assassin Diner), into her living room. She smiled kindly and gestured towards the dining table, where plates and cutlery were already set.

Yuki bowed her head slightly and responded with a polite tone, "Thank you very much for your hospitality, Ms Midoriya. You are very kind." She smoothed out her skirt and took a seat at the table.

As Izuku observed the interaction, autopilot bringing him to a seat across from Haro, his mind began to race. "Okay, Izuku, let's not jump to any conclusions. There's just no way," he thought to himself. "She doesn't look anything like the woman who attacked Aizawa. That woman had red hair, and Haro's hair is black. Besides, why would a villain be at our house for dinner? It doesn't make any sense!"

"Izuku?" Inko's voice snapped him out of it. She had placed a hand gently on his shoulder and looked at him with concern. "Are you alright, dear? You seem distracted."

"GAH! Oh uh sorry mom," Izuku said, trying to regain his composure. "I was just lost in my own head for a moment."

His mother laughed sweetly, giving him an affectionate look "We might lose you in there for good one of these days," she teased.

Meanwhile, Yuki's mind was also busy with perplexing thoughts. But unlike Izuku, she had been trained to separate her thoughts and actions to maintain a facade of normalcy. As 'Yuki', she outwardly thanked Inko for inviting her into her home and complimented her on the food. As 'Diner', her thoughts raced with questions and doubts.

"Why does Ms. Midoriya's son look so familiar to me? Where have I seen him before?" she wondered silently. "He couldn't have been at the boardwalk when I eliminated Captain Daesha. That was an exclusive event for adults, and he doesn't strike me as the kind who would sneak in. Could he have been at the gala event? Or, the UA incident? But that's impossible, he's in the support course, not heroics."

As Inko served their meals, Yuki said with a polite smile, "This all smells wonderful, thank you Ms Midoriya."

Inko smiled warmly back at her, feeling a maternal bond with the young girl. "Yuki, you're in my home, you can call me Inko, remember?" she reminded her gently. For some reason that the ruthless assassin could not fathom, it seemed that this kind grocery store worker had decided to take her under her wing.

As the food was served, Yuki casually reached for the cutlery that Izuku had previously set on the table, and switched the positions of the fork and knife, placing them in their proper order according to etiquette. As she did so, a flash of recognition sparked in Izuku's mind and he frowned to himself. He felt a surge of dread as he realised that his initial suspicions about Yuki might have been correct…

He quickly shook his head and tried to rationalise his thoughts. "No, no, no! That's ridiculous! She just knows how to set the table properly, that doesn't mean she attacks people with forks! That's absurd, Izuku! Don't jump to conclusions based on such flimsy evidence! If only I could find out where she got that head injury…"

Over dinner the three of them enjoyed their meal, with Inko and Yuki engaging in light conversation with Izuku occasionally being made to participate by his mother.

Later, Izuku bit his lips nervously, feeling a knot in his stomach. He decided to take a risk and screwed his courage to the sticking place. "H-Haro, I'm sorry to pry, but… are you alright? Your head, I mean."

His mother looked at him with a disapproving expression. "Izuku, that's not a very polite thing to ask at the dinner table. You shouldn't make our guest feel uncomfortable."

"It's quite alright," Yuki said with a soft smile. "I appreciate your concern. I'm fine, really. It was just a minor injury from a self defence class I took recently."

"Yuki doesn't have a combat quirk either, dear. She's just like you in that regard. Oh! Maybe she could teach you some techniques for the sports festival! You could use some extra training, don't you think?"

"Oh m-maybe. That would be nice. But I don't think I'm getting very far in the festival anyway. I'm not very good at fighting."

Yuki politely asked Izuku, feigning an interest but with an ulterior motive. "May I ask what your quirk is? If you don't mind sharing, of course." "This could be the student who deflected my kill shot against Aizawa."

"My quirk is called Green Hair. It's… well, it's exactly what it sounds like." Izuku said sheepishly. "What's yours?"

"Tactile Polygraph. It's a very weak lie detector quirk. It only works if I can touch someone's pulse." Ironically, this was a lie in itself that Diner had used many times in her civilian life. She rarely had to demonstrate it, unless someone was very suspicious of her. And even if she did, she had learned to read the subtle signs of deception in people's body language. A faster heartbeat, a flaring nostril, a blink too many. Even for harmless lies, there was always a tell.

She smiled innocently and reached for his hand. "Do you mind if I try it on you? It's harmless. I promise."

—

"Yo, Eraser, you gonna get me down from here or you just gonna stand around suckin' ya thumb?"

"Shut your trap, Skullcap. I explicitly warned you to stay away from this business. Frankly, you should count yourself lucky that it was Mayhem who caught you dealing. If it had been me, you wouldn't even be conscious right now."

Skullcap found himself entangled in a makeshift contraption resembling Eraserhead's capture device, though lacking the same tensile strength. If he had a nickel every time he ended up in this situation with the underground hero, he'd have two nickels. Which isn't a lot, but it's weird that it had happened twice. Just as Skullcap began to spin away from him, Aizawa seized his bony skull and forcefully turned it to face him.

"Where did she go?" Aizawa asked with an emotionless expression on his face.

"We didn't exactly have a friggin heart-to-heart, Eraser!" Skullcap protested."She just called me Sans Undertale, whatever the hell that means, strung me up like a pinata, called the cops and left!"

Aizawa narrowed his eyes and tightened his grip on Skullcap's head. "Are you sure you didn't catch a glimpse of which direction she went?" he asked icily. "I did promise I was taking the head next time."

"Alright, alright! Geez, you heroes have no chill," Skullcap relented. "She was heading towards Toshei Street."

"Thanks for the cooperation," Aizawa smirked slightly and released his grip, swiftly deploying his capture scarf to propel himself onto the rooftop, leaving Skullcap dangling in mid-air.

"Hey! You just gonna leave me up here?!" Skullcap shouted after him. "Heeeey!"

Eraserhead scanned the night sky as he leaped from one rooftop to another, heading towards Toshei. He had seen her handiwork all over the city. Three villains were captured and left for the authorities in a matter of hours, and try as he might he couldn't deny her skill and speed. She was a formidable fighter, even if she was working outside the law.

In mid swing he spotted two thugs trying to rob a woman in a dark alley below, and quickly descended and immobilised them effortlessly. It was as though he was subconsciously trying to one-up Mayhem. He didn't bother to say anything as he left them hanging from a lamppost, there were bigger fish to fry.

Why was she doing this? Was she the same person who had attacked him at UA? He had to find out the truth and stop her regardless.

Eraserhead came to a stop on the edge of a small building and looked over at the sign reading Toshei Street, a street lined with small shops and cafes, likely frequented by the denizens of the suburban buildings a short walk away. It was unassuming, but he knew better than to let his guard down.

Quietly, he muttered to himself, "I don't care who you are or what you want. You're not getting away from me. I don't let vigilantes run wild in my city."

"Well you're doing a great job so far!"

His body reacted on instinct, lightning-fast reflexes honed by years of experience. Aizawa swiftly spun around, his capture scarf whirling through the air, ready to ensnare the intruder. But instead of finding his target within his grasp, his eyes locked onto the sight of Mayhem gracefully leaping a dozen feet into the air, defying gravity with ease. She embodied the description provided by eyewitnesses, although he felt they may have exaggerated her short stature.

Recoiling his capture scarf, Eraserhead poised himself for a second attempt. Yet, before he could make a move, Mayhem's voice, modulated and digitised, broke the tense silence once more.

"Hey, cool it, dude!" Her hands were held out in a gesture of peace, as though she was trying to calm a wild beast. "I just want to talk! I know you've been looking for me." There was an undeniable confidence in her demeanour. "Figured this would be easier than you breaking into my house."

"So you live in a house," he replied, his posture gradually relaxing, although his guard remained up. Things seemed safe, but he knew better than to let his defences drop completely.

"No, dude, I live in a big cave under a mansion." Although her eyes were hidden behind the mask, Eraserhead caught a glimpse of an eye roll. The mask itself appeared different from what had been described to him - a full helmet instead of the partial covering. Was this an updated costume?

Mayhem pressed on, "I've been doing your job for you, Mummymon. The woman who attacked you - I managed to find a lead."

Intrigue flashed in Eraserhead's eyes. How had Mayhem accomplished what he couldn't? "How? The trail went cold for me almost immediately."

"Trade secret! I have eyes in a lot of places." Her response carried a hint of suspicion. "But truth be told, I've hit a dead end. Over the past four months, there have been four murders in and around Musutafu. The furthest one was about a kilometre outside the city limits, but the cases were assigned to this precinct."

Eraserhead's brow furrowed, waiting for the next part. "And here's the kicker," Mayhem continued. "Each victim had very similar wounds."

"Forks." Eraserhead stated matter-of-factly.

Mayhem tilted her head, her masked gaze meeting his. "No need for the language, but yeah," she replied. "The cops don't seem to connect the dots. Each murder has been attributed to some other crazy explanation!" She said, gesticulating wildly as she paced the rooftop. "But come on, how many times can four uniform holes in a person's throat be a coincidence?"

"How did you find all this out?"

A sly smirk played on Mayhem's lips, a testament to her resourcefulness. "Let's just say the police aren't exactly experts in cyber security." She deliberately withheld the fact that she had peered through a window, from six blocks away, to catch a glimpse of their computer screen. "But there's something deeper at play here, something more to the police's involvement."

Eraserhead found himself completely at ease now, a sense of trust slowly building within him. "Tsukauchi," he muttered, realisation dawning on him. "He's been called away to a conference at the start of each of the past four months."

Mayhem nodded in agreement. "I think they're deliberately diverting his attention, ensuring that these cases are assigned to someone else - someone who isn't actively investigating these murders. This is where I need your help. I don't have an insider connection with the police. Buuuut… You do."

"You want me to find out who these cases are assigned to, or who has been tampering with the reports."

"Bingo bongo." Mayhem replied.

Aizawa nodded solemnly, accepting the gravity of the task at hand. "I'll help," he stated, his voice firm. "But let me offer a word of warning. If this investigation leads us to crooked cops, remember that you're already known to them. If they catch wind of your presence, they won't be as lenient as I am. You should consider turning yourself in before this escalates."

"Ahh yeah sorry, no can do. Thing is, I'm pretty damn good at this." With that, she gracefully leaped backward off the edge of the roof, narrowly evading Eraserhead's capture scarf once again. As she descended toward ground level, Mei Hatsume silently offered her gratitude to the science gods for the functionality of her longfall boots.

—

"I'll start with a simple question to acclimatise my quirk to your pulse's rhythm, is that alright?" Yuki inquired, her eyes scanning Izuku's face for any flicker of deceit. He had claimed to possess a quirk related to green hair, and this initial test would help alleviate her lingering suspicions. However, even with her keen perception, deciphering this boy's true nature seemed like a challenging puzzle. Yuki could recognise that base level of anxiety in a person, which had an unfortunate side effect of making everything they do seem slightly suspicious.

With a gentle yet firm touch, Yuki placed two of her fingers on Izuku's upturned wrist, "Is your name Izuku Midoriya?" she asked.

"Yes," Izuku responded without hesitation, his pulse quickening momentarily before settling into a steady and rhythmic beat.

"True." Yuki continued her line of questioning, "Is your quirk called Green Hair?"

For a fraction of a second, Izuku hesitated, his eyes reflecting a momentary internal struggle. Yet, he answered, "Yes."

Yuki observed his pulse carefully, her senses attuned to the subtle shifts beneath her fingertips. His heartbeat remained steady and unwavering. It appeared that Izuku was indeed speaking the truth. Maybe he wasn't involved in the incident concerning Aizawa, after all. Despite her best efforts to maintain a neutral composure, a faint frown tugged at the centre of Yuki's eyebrows, betraying the nagging doubts that still lingered within her. "True."

Sensing the change in Yuki's demeanour, Izuku couldn't help but voice his concern. "Is everything okay?"

Yuki swiftly composed herself, regaining her neutral facade. "Yes," she replied, her voice tinged with a hint of forced reassurance. "Apologies, I was just ensuring the compatibility of my quirk. Sometimes, it can give false readings shortly after a person has eaten."

"Oh, I didn't know that!" Inko said with interest, "Isn't that fascinating Izuku? Izuku is a little of an expert on quirks."

A tinge of embarrassment clouded Izuku as he responded, "Oh, yeah, I've always found quirks kind of cool." He quickly shifted the focus back to Yuki. "Your quirk could be really useful for police investigations, Haro."

Yuki nodded appreciatively. "Perhaps," she mused, "It's not a line of work I've ever pursued, though." She then turned her attention back to Izuku, her voice gentle yet insistent. "May I use my quirk one final time?"

Izuku hesitated for a moment, his mind racing to find the best response. "Oh, I guess so," he replied, trying to maintain an air of nonchalance. "I don't mind."

Yuki's eyes locked onto his, her gaze piercing yet calm. "Did you enjoy the tempura?" she inquired, her voice steady and measured.

Izuku's heartbeat quickened imperceptibly, a subtle sign of his unease. "Yes," he answered, voice wavering ever so slightly.

"Lie," Yuki stated matter-of-factly, her words cutting through the air like a surgeon's scalpel.

Inko's eyes widened in shock. "Izuku!"

"I'm sorry, Mom!" Izuku stammered, his words rushing out in a flurry. "I just thought the vegetables were a little overcooked!" He desperately attempted to backtrack his criticism, hoping to salvage his mother's feelings. To his relief, Inko laughed away the minor critique.

"Oh, Izuku, how could you!" she playfully exclaimed, placing the back of her hand against her forehead in an exaggerated display.

Yuki's laughter mingled with the others, a rare and genuine expression of amusement from the typically composed assassin. In that moment, she felt a swell of happiness that this family was innocent and untouched by the dark web of her clandestine activities.

Amidst the laughter and lighthearted banter, a silent battle raged within Izuku's mind. He couldn't shake the nagging thought that he had lied about his quirk, wondering why Yuki hadn't detected his deception. Unbeknownst to him, the answer lay within the intricate workings of his own quirk.

As Yuki delicately placed her fingers on Izuku's wrist, a remarkable transformation unfolded beneath her touch. The musculature and bone of his wrist shifted and transformed, into an intricate piece of clockwork machinery. A delicate, pulsating mechanism, subconsciously synchronising itself to mimic a normal heartbeat rhythm, all entirely hidden beneath the skin.

But as far as Izuku knew, it was just a fluke - a fleeting moment when his secret was almost exposed to a stranger. The thought of anyone, even his own mother, discovering his hidden quirk sent a surge of unease through him. Yet, he couldn't help but question his own apprehensions now his secret came so close to being revealed. Why was he hesitating to tell his ever-supportive mother? She had always praised his interests, celebrated his achievements, and guided him towards his dreams. So why the lingering fear of her knowing?

With dinner coming to a close, Izuku and Inko bid farewell to their newfound friend, though a trace of suspicion still lingered in Izuku's mind. But something about Yuki seemed trustworthy, her intentions genuine. As she departed their apartment, Izuku's thoughts swirled, contemplating the complexities of his own fears.

At that moment, Izuku came to a decision.

—

Eraserhead could easily pursue Mayhem as she leaped from that rooftop. She knew that, so the fact he hadn't followed her seemed like a good indicator he was on her side. Actually, It could be pretty fun to have some crime fighting partners. Someone to share this with. And if those crooked cops do try to come after her, some backup would come in useful.

At that moment, Mei came to a decision.

—

"I'm going to tell my mom about my quirk."

—

"I'm going to tell Izuku I'm a vigilante."