A Hero in a Demon School!!!!

"Opera! Send the next wave!" Izuku called out, panting heavily. He stood at the center of the mansion's underground training ground, his black tank top clinging to his sweat-soaked body and his green eyes alight with determination.

At the edge of the room, Opera stood calmly beside a machine capable of launching objects of various sizes at different speeds. Right now, it was loaded with volleyballs and cranked to its maximum limit.

At Izuku's signal, Opera activated the machine. Eight volleyballs rocketed toward him at high speed. Izuku's eyes narrowed, tracking their trajectories for just a split second before he sprang into action.

He leaped over the first ball, slid under the second, twisted his body to avoid the third and fourth, and then, 'Shoot Style: Lunar Air Smash!' His leg arched back in a perfect vertical roundhouse kick, infused with 45% of One for All. The compressed air blast from his kick sent the remaining balls hurtling into the back wall with a resounding thud.

'Great work, Izuku,' Nana's voice echoed in his mind. 'Rumi's training must've been really effective if you're pulling off moves like that,' she said and Izuku could practically feel the shit-eating grin in her tone.

'Yeah,' Izuku thought with a tired smile, brushing a hand through his damp hair. 'Her teaching style is… intense.' The memory of their first meeting brought an unbidden, genuine grin to his face.

******

Flashback

It had been two days since Izuku returned from his solo run and at the moment, he was alone in Gym Gamma, working on his kicks, since his usual training partners had already called it a day.

Then, when he was getting ready for another round, a woman with bunny ears approached him with a thoughtful expression.

"Hey, Mirko. Do you need something?" Izuku asked, wiping sweat from his brow.

Rumi stared at him for a moment before bluntly declaring, "Your kicks are shit, and your technique is dog water."

"Oh… okay," Izuku stammered, too stunned by her blunt opinion to respond properly.

"That's why I'm going to take you under my wing and make you the second-best kicker in this country," she said with a confident grin.

"Okay," he replied absentmindedly, then did a double take. "Wait, why?"

"Because you'll be fighting on the front lines with me, and I'm not teaming up with someone who can't even kick properly," she stated matter-of-factly.

Upon hearing that, Izuku looked down and clenched his fists. 'She is right. I can't hold back people I am fighting with because of my inability to do something.' Then, Izuku looked at her with determined eyes. "Mirko, please help me to improve my shoot style," he said, bowing to her.

But then, suddenly, he received a smack on the head from Mirko's metal arm. "Geez, kid, relax! I said I would train you, didn't I?" she said with an exasperated expression. Then her face softened as she ruffled his hair. "Listen, kid, I know you have a world riding on your shoulders right now, but you don't need to do everything all by yourself," then she looked into his eyes and flashed a confident smile. "And I don't care how hypocritical it sounds, but you can count on adults around you to save your ass."

"Yes, ma'am!" Izuku replied with a smile, only to get smacked again.

"I told you to relax! And drop the formalities. Just call me Rumi," she said as she headed for the door. "Your training will start tomorrow, same place, same time," then, as she was just about to exit the gym, a devilish smile appeared on her face. "By the way, I noticed those bunny ears on your costume; they actually look quite cute on you," she said and left the room laughing out loud, leaving a red-faced Izuku behind who was trying to form words from his mouth.

******

As the memory faded, Izuku blinked back into the present to find Opera approaching with a towel.

"Izuku-sama, that should be enough for today," Opera said, their voice calm as they surveyed the training ground littered with volleyballs and debris.

"Yeah, thanks. And sorry for the trouble," Izuku replied, taking the towel and wiping his face. He hesitated for a moment before asking, "So… do you think I have a chance?"

Opera placed a hand on their chin while their eyes flickered thoughtfully. "It's hard to say since we don't know who Ms. Ameri will choose as your opponent. But based on your progress and skill, I believe you'll do quite well."

"Thanks," Izuku beamed at him, "I will take all the positivity I can right now." 

Opera's ears twitched slightly. "Izuku-sama, you should go take a bath. I'll prepare breakfast in the meantime."

"Got it!" Izuku nodded, slinging the towel over his shoulder as he followed Opera out of the underground training ground.

******

"Good morning, Izuku-kun. How did your training go?" Sullivan asked, smiling warmly as Izuku settled into his seat at the breakfast table.

"It went well, I think," Izuku replied, picking up his utensils. "My movements are still a little stiff, but overall, it was a solid session."

"That's good to hear," Sullivan said, taking a leisurely sip of his tea. "So, how do you plan to spend the rest of your day?"

"Well…" Izuku began, shoveling a bite of food into his mouth. "Since we don't have school today, I thought I'd go over some study materials I got earlier this week. Other than that, I don't have much planned."

"In that case, why not accompany Opera on their little trip to Magical Street?" Sullivan suggested.

"Magical Street?" Izuku asked curiously, holding out his plate for seconds.

"It's a well-known shopping district nearby," Opera explained as they refilled his plate. "I need to pick up some items for the house. You're welcome to join me if you'd like."

'Izuku, I think it's a good idea,' Nana's voice chimed in his mind. 'Going along could help you learn more about this world and its economy.'

Izuku mulled it over for a moment before nodding. "Sure, I'll join you," he said.

"Excellent!" Sullivan beamed, clapping his hands together. "And while you're at it, pick up a few things for yourself."

Izuku tilted his head, smiling sheepishly. "You've already given me so much, Grandpa. I don't think there's anything I really need right now."

"In that case, what about a custom uniform?" Sullivan suggested, his eyes sparkling with excitement.

"A custom uniform?" Izuku echoed, his curiosity piqued.

"Yes. I'm sure you've noticed that many of your peers use custom uniforms. Why not have one made for yourself as well?" Sullivan asked.

"Hmm, that sounds interesting so why not?" Izuku said with a shrug. He turned to Opera. "When do we leave?"

Opera rested a hand under their chin thoughtfully. "We'll head out in an hour. I'll finish up the remaining chores first."

"Okay," Izuku replied, then looked back at Sullivan. "Are you coming with us?"

Sullivan's expression shifted dramatically as metaphorical storm clouds gathered over his head. He slumped in his chair, whining, "I wish I could, but I have important meetings today. Unless…" He perked up, a sudden mischievous grin appearing. "What if Grandpa skips all those boring meetings and spends the day with his grandson instead?"

"Absolutely not," Opera interjected, shutting down the idea immediately. "I'll accompany Izuku-sama, and you will attend your meetings."

Sullivan clutched Izuku in an exaggerated hug, dramatically wailing, "You're so cruel, Opera! All I want is to spend time with my beloved grandson!"

Opera raised an unimpressed brow. "Do you really want to set a bad example for Izuku-sama by shirking your responsibilities?"

Sullivan froze, then straightened his posture with newfound determination. "You're right, Opera. As a grandfather, I must be someone Izuku-kun can look up to!" Adjusting his tie, he grabbed his briefcase. "Izuku-kun, Opera, I'll see you both this evening!"

As Sullivan left, Izuku chuckled softly. "It must be tough taking care of two children, huh?"

"It's part of the job description," Opera replied smoothly, sipping their tea. "Well then, Izuku-sama, I'll see you in an hour."

******

"Whoa!" Izuku exclaimed, his eyes wide as he took in the bustling market. "This place is incredible! There are so many unique things here!"

"That's to be expected," Opera said, walking beside him. "This is one of the largest markets in the Netherworld. By the way first, we'll stop to order your new uniform. Is that alright with you Izuku sama?"

"Sure," Izuku said. As they both walked through the Magical Street, Izuku took notice of the various items displayed outside the shops. What fascinated him more was the fact that many of them resembled items from the human world.

'A lot of these items resemble things from Earth,' Izuku thought

'Yeah, quite a lot actually,' Nana added, 'honestly, if you drop any of these demons in our old world, no one will even bat an eye or think that they don't belong in the overworld.'

'It's fascinating how two entirely different worlds can have such similarities,' Izuku mused. 'Makes you wonder if our old world had something like the Netherworld as well.'

'Maybe,' Nana replied, her voice tinged with somber reflection. 'Though I'd say we've already faced the worst demons our world had to offer.'

Just then, Opera's voice pulled him out of his internal conversation with Nana. "Izuku-sama, we've arrived," they announced, stopping in front of a sleek, elegant shop.

Izuku hesitated as he looked up at the grand storefront. "Opera… are you sure we should shop here? This place looks really expensive."

"Yes, this place is a little expensive, but that won't be a problem," Opera said in a tone that left no room for argument. "In fact, as the grandson of Sullivan-sama, you will have to visit many similar places in the future."After that little conversation, Opera and Izuku walked inside the store.

******

As they stepped inside, the opulent interior immediately captivated Izuku. Gleaming marble floors reflected the warm light of ornate chandeliers, and rows of luxurious clothing were arranged with an almost artistic precision. Employees moved gracefully through the store, tending to customers with practiced poise.

One such employee, a woman with neatly tied hair and a polite smile, approached them. "Welcome, esteemed guests. How may I assist you today?"

"We'd like to order a custom uniform," Opera stated.

"Of course," the employee replied, maintaining her professional demeanor. "But I must inform you, custom uniforms can be quite expensive."

"That won't be an issue," Opera said calmly. "You can send the bill to Sullivan-sama's mansion."

The moment Sullivan's name was mentioned, the employee's eyes widened in surprise, and her smile faltered for just a moment. She quickly regained her composure and bowed deeply. "Please wait here for a moment. I'll fetch my superior." With that, she turned and hurried toward the back of the store.

Izuku shifted awkwardly, glancing at Opera. "What is going on?" he whispered.

"Nothing that we should be worried about," Opera replied. "This is just how the general public reacts to Sullivan-sama's name. They don't want to offend or inconvenience him or his closed ones, even for trial matters as such."

Moments later, the employee returned, this time accompanied by a tall, elegant woman dressed in a sharp black suit.

"Good afternoon. "My employee mentioned you're associated with Lord Sullivan. Do you have any proof of your connection?" the woman asked.

Opera reached into their pocket and produced a ring adorned with Sullivan's emblem. Holding it up, they said, "I am Opera, Lord Sullivan's security demon, and this is Izuku-sama, his grandson."

Izuku stepped forward and gave a small bow. "Hello, ma'am. It's a pleasure to meet you."

"My, my! Polite, aren't you?" the woman said with a smile. "I'm Rose, the owner of this establishment." She glanced at her employee. "You may return to your duties. I'll personally assist our guests."

With a graceful gesture, Rose led them upstairs to a private fitting area on the second floor. Once they were seated, she turned her attention to Izuku. "Now then, young man, what kind of uniform are you envisioning? Do you have a design in mind?"

"Actually…" Izuku began, explaining the design he and Nana had brainstormed while waiting for Opera to finish their chores at home earlier.

Rose listened intently, nodding occasionally. "That's a fantastic idea! We can definitely work with that. Then she motioned to a nearby employee, who immediately stepped forward with a measuring tape and a notepad. As the employee took Izuku's measurements, Rose continued, "Your design has a good balance of practicality and personality. It'll suit you well. Leave the rest to us."

Once the measurements were done, Rose escorted them back to the entrance. "We'll deliver the finished uniform directly to Sullivan-sama's mansion," she assured with a professional smile. Then, turning to Izuku, she added, "By the way, young man, I never caught your name."

"Izuku Midoriya," he said with a polite bow. "Thank you for your help today."

"The pleasure was all mine," Rose replied, producing an elegant business card seemingly out of thin air. "If you ever need anything else, don't hesitate to reach out." She gave him a playful wink before disappearing back into the store.

******

After leaving the shop, Izuku and Opera continued wandering through the bustling market, crossing items off their list one by one. As they went, Opera used the opportunity to teach Izuku about the local economy—how to handle the Netherworld's currency and spot high-quality goods. He even got a quick lesson on spotting counterfeit goods and avoiding shady merchants.

As the sun began to dip below the horizon, painting the market in warm golden hues, Izuku turned to Opera with a grateful smile. "Thanks for bringing me along today. I had a lot of fun, and I learned so much."

"I'm glad you enjoyed it, Izuku-sama," Opera replied, glancing at the sky. "But it's getting late. We should head back—I still need to prepare dinner."

"In that case, let me help," Izuku offered, his smile widening. "Think of it as a thank-you for today."

Opera raised an eyebrow, amused. "That's a surprise. You know how to cook?"

"I mean, I'm no expert, but I can manage something edible if my life depends on it," Izuku said, scratching the back of his neck sheepishly.

"In that case, I'll gladly accept your help," Opera said with a small smile. "But fair warning—Netherworld ingredients can be... quite unique."

And so, Izuku's weekend concluded with a bit of cooking and quality time with his new family, setting the stage for Ameri's big challenge awaiting him in Monday's Mock Battles Exam.

******

Alice's House

"Big brother is so amazing!" Voile exclaimed, her voice bubbling with admiration.

"Yeah! He's the greatest person in the world!" Lily agreed, her eyes sparkling with awe as they watched their older brother, Asmodeus Alice, training with his flames.

With a flick of his wrist, Alice launched another blazing fireball at a distant target. As the flames soared through the air, an elderly butler approached, bowing with respect. "Alice-sama," he began, "Lady Amaryllis has returned from her work and wishes to see you."

"Got it, David. I'll be there in a minute," Alice responded, his focus unshaken as he prepared yet another fireball, launching it at the next target.

David hesitated for a moment, then spoke again, his voice tinged with concern. "Forgive me for interrupting, Alice-sama, but you've been training for hours now. Perhaps it's time to take a break? You've accomplished quite a lot today."

Alice, still absorbed in his training, muttered under his breath, "Yeah, yeah, I know. Just one more push." With a deep breath, the flames in his hands roared to life, swirling in an intricate dance of heat and power. He compressed the energy tightly before hurling the fireball with perfect precision. The resulting explosion obliterated the target completely, turning them to char.

"Yaaa!!!" "So cool!!!" Voile and Lily cheered, clapping enthusiastically as they watched their brother's display of power.

"That was quite a spectacular attack, Alice-chan!" a cheerful voice chimed in from behind and before Alice could even react, he was suddenly tackled into a bear hug by a tall, elegant woman with long, flowing pink hair.

"Mother!" Alice growled, his face reddening as he struggled against her tight grip. "Get off me! I'm covered in sweat—how can you not find this disgusting?"

Amaryllis grinned mischievously, pinching his cheeks affectionately. "Darling, I'm the one who gave birth to you. Nothing about you could ever disgust me." Alice sighed, his patience already wearing thin as she continued. "Still, I must admit, I've never seen you this passionate about training. What's got you so fired up?"

Alice straightened, a cocky smirk spreading across his face. "It's because, for the first time in ages, there's someone who can actually keep up with me. And I'm not about to lose to him."

"But how could anyone possibly compete with you? You're the best in the whole Netherworld!" Voile asked, her head tilted in confusion. Lily nodded in agreement, equally perplexed.

Alice crouched down and affectionately ruffled their hair, a fond smile on his face. "Don't worry, girls. I'll keep working hard to stay on top—just for you two."

Amaryllis watched the scene unfold with a warm, affectionate smile, but her curiosity was piqued. "By the way, Alice, who is this new rival of yours?"

Alice shot her a suspicious look. "Why do you want to know?"

"I'm just curious," Amaryllis said, pouting dramatically. "I want to meet the boy who's managed to motivate my Alice so much."

Alice let out a long, exasperated sigh. "There's no need for you to meet him or any of my friends, for that matter." He paused before reluctantly answering, "But if you really must know, his name is Izuku Midoriya. And, just so you're clear, he's Sullivan-sama's grandson. So don't do anything weird."

Amaryllis gasped theatrically, feigning offense. "Alice, how could you say such things in front of my precious daughters? What if they start thinking badly of me?"

"Don't worry, Mom! We love you!" Voile said with a bright smile, running over to hug her mother tightly.

"Yeah, me too!" Lily added, following her sister's lead.

"My sweet little butterflies, I love you both so much," Amaryllis said, wrapping her daughters in a warm, loving embrace.

Meanwhile, Alice rolled his eyes at the scene and muttered under his breath, "I swear, this family is going to be the end of me," before heading inside to freshen up.

"By the way," Amaryllis called out to him as she walked away, her curiosity still lingering. "What exactly is a friend?"

Alice paused in his tracks, turning back to face her with a raised eyebrow. "Don't ask me, I'm still trying to figure it out myself." With that, he disappeared inside the house.

******

Clara's House

In the spacious backyard of the Valac estate, a sprawling farm stretched across the land, its neatly arranged rows teeming with a wide variety of fruits and vegetables. Clara, as cheerful and lively as ever, moved from plant to plant, picking the ripened produce and placing it into the basket slung over her back. Her humming and soft singing filled the air, creating a harmonious melody as she worked.

Nearby, her mother, Mrs. Valac, watched her with a warm smile. She had always known Clara to be energetic and full of life, traits that ran deep in their family. But recently, there was something even brighter about Clara's demeanor, something her mother couldn't help but notice.

"Clara, did something happen?" Mrs. Valac asked, raising an eyebrow with a hint of curiosity in her voice. "You seem... even more cheerful than usual."

Clara paused for a moment, glancing up at her mother with a playful tilt of her head. "Really?" she asked innocently. Then she shrugged it off, her smile widening. "I'm just happy because tomorrow I'll get to play with Azz-Azz, Eo-chan, and Izu-kun!" she declared, her face lighting up at the thought.

Her mother's eyes widened in surprise at the mention of Clara's peers, as this was a subject Clara rarely discussed at home. It was unusual for Clara to talk about others, and Mrs. Valac felt a tug of curiosity. "Clara, who are these people?" she asked and immediately noticed a different kind of glow appear on Clara's face, her smile stretching wide as she began eagerly explaining.

"Azz-Azz is really strict sometimes, and he does scold me, but he never says anything mean or tells me to go away, even when Izu-kun is busy with something else."

"Eo-chan is super nice too! She brings me sweets, talks to me about clothes, and takes so many pictures of me." Clara pulled out her phone from her pocket, showing her mother a gallery of pictures, each one more adorable than the last. They were candid shots of Clara, some taken from afar, others close-up, all full of charm.

"Ohh!!! And then there is Izu-Kun and he is like the best you know," now the glow on Clara's face was tripled, "he is the first person who actually played with me. He lets me ride on his back and doesn't get angry when I play pranks on him and-" Clara's words tumbled out rapidly, as she went on, recounting every little thing she had done with Izuku over the past week, from their playful adventures to the quiet, heartfelt moments. Mrs. Valac listened intently, a smile tugging at her lips as she observed how happy Clara was.

Finally, after a few minutes of rapid chatter, Clara paused to catch her breath, but the happiness never left her face.

Mrs. Valac's smile softened with warmth as she looked at her daughter. "I guess you've finally found the demons you belong with," she said, her voice full of understanding and affection. "In that case, why don't we invite them over next time you all have free time? I'd love to meet these peers of yours."

Clara's eyes sparkled with joy, her face lighting up even more. "Really!? You'll meet them?" she exclaimed, her voice practically singing with excitement.

"Of course, dear," Mrs. Valac replied, gently patting Clara on the head. "Now, let's finish picking the rest of these vegetables, shall we?"

Clara beamed at her mother's words and nodded eagerly. "Okay, Mom!" With that, the two of them continued their work in the garden, the sound of their laughter and lighthearted conversation blending with the peaceful hum of nature surrounding them.

******

Eiko's House

The sun had already dipped below the horizon, and the twin moons of the Netherworld bathed the night sky in their eerie light. Inside the Oni household, Eiko Oni lay sprawled across her bed, absorbed in a book. The calm evening was broken by her mother's voice calling from downstairs.

"Eiko, you have a guest!"

'Guest? At this time?' Eiko thought to herself. Eiko thought to herself, puzzled. She closed the book with a sigh and headed downstairs, only to be greeted by a familiar face.

"Gaako! What a surprise!" Eiko exclaimed, her eyes lighting up. Without thinking, she rushed forward and pulled her friend into a tight hug. "Wait, what brings you here at this hour?"

Gaako smiled, a bit sheepish, and shrugged. "Well, I was just going over some study material, but I needed a break. So, I thought I'd stop by."

Eiko's mother, who had been sitting on the couch, looked at the scene with a bemused smile. "Eiko, you could learn a thing or two from her," she commented casually.

"Mom!" Eiko groaned in embarrassment, her cheeks flushed.

From the kitchen, Eiko's father's voice rang out, cheerful as always. "Come on, dear. It's only the first week of school. Don't be so hard on her."

"Dad! You're home already? How was business today?" Eiko asked, walking into the kitchen where her father was preparing dinner.

He gave a casual shrug. "Business as usual. Nothing exciting happens at the diner, you know."

"Typical," Eiko muttered before turning back to Gaako. "So, how's school treating you?"

"Good, I guess," Gaako replied, though there was a noticeable bitterness in her tone. "But nothing exciting like your class."

"Wait, what class are you in, Eiko?" her mom asked, genuinely curious.

"Misfit Class," Eiko said nonchalantly, not sensing the subtle tension in the air.

"Misfit Class?" Her mother raised an eyebrow. "What kind of name is that? And what did you do to end up in such a strange class?"

"Maybe it's because of the kind of people she's been hanging out with lately," Gaako said suddenly, her voice carrying an edge.

Eiko turned, her eyes widening in surprise. "Gaako, what are you saying? You know Izuku and the others aren't bad people."

"I don't know, okay," Gaako said, her tone sharper now. "I just don't want you to get left behind when they move up in their lives," she said as Eiko's eyes narrowed, her patience wearing thin.

"Wait a minute—what's going on here?" Eiko's mother stood up, her concern evident. "Eiko, are you hanging around with bad company?"

"No! Of course not, Mom!" Eiko rushed to defend herself, her face flushed with frustration. "Izuku saved my life on the first day of school, and Azz even apologized to me for that incident. And Clara is Clara—she can't be a bad person!"

Gaako sighed and rubbed the back of her neck, clearly reluctant. "Izuku Midoriya is Sullivan-sama's grandson, and Azz is Asmodeus Alice," she said, her voice flat.

At the mention of those names, Eiko's mother's face drained of color. There was a sharp clattering sound from the kitchen as a dish fell to the floor. "Izuku did save her during his fight with Asmodeus when a stray attack nearly hit her," Gaako added. "But it was their fault to begin with."

"And... this Clara girl?" her mother asked, her voice now tinged with suspicion.

"Clara Valac," Gaako said dismissively. "She's an idiot."

"Take that back!" Eiko snapped, glaring at her friend. Her voice was fierce, unlike anything Gaako had heard from her before. "Clara might do some silly things every now and then, but she is not an idiot!"

Gaako flinched, caught off guard by the sudden intensity. "Okay, okay, sorry. I didn't mean it," she mumbled, her tone now apologetic.

However, Eiko's gaze didn't soften. "Also, Gaako, please leave," she said firmly, the words sharp. "I don't want to talk to someone who's badmouthing my friends."

"Wait, Eiko—" Gaako started, but Eiko cut her off, her voice cold.

"No, just go. I'll talk to you later, but not right now."

Gaako stared at her for a moment, hurt and surprised by the sudden distance. With a defeated sigh, she turned to leave. The door clicked softly behind her, and the house fell into an uncomfortable silence.

Eiko's mother let out a long, weary sigh and walked over to the couch. "Eiko, come here for a moment," she said softly, motioning for her daughter to sit beside her. Eiko hesitated but obeyed, sitting next to her mother. Her mother's expression was concerned but understanding. "Listen, it's not that I don't trust you, but are you sure you're not associating with bad people?"

Her mother studied her for a moment, her face softening as she took in her daughter's words. After a long pause, she sighed. "Alright, I believe you. But if anything ever goes wrong, if they hurt you in any way, you come to me. I'll show them a mother's wrath, no matter who their parents are."

Eiko smiled gratefully, feeling a warmth spread in her chest. "Thanks, Mom. You're the best."

Her mother chuckled, ruffling her hair affectionately. "Yeah, yeah. Stop buttering me up and go call your brother for dinner."

With that, Eiko felt the tension leave her body, and she gave her mother a quick hug before heading toward the upper floor to call her brother for dinner.

******

And thus, the eventful weekend came to an end, and now it was time for the Mock Battles Exam.

******

[A/n: I know many people don't like OCs but I am trying not to rewrite Iruma-Kun's story with Izuku's skin so there will be few OCs in the story and I hope you will like them.]