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English
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Sonic The Hedgehog x MHA/BNHA Crossover Fanfics, Sonic the Hedgehog 🦔 Crossovers Fanfics
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Published:
2025-04-21
Updated:
2026-08-28
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27,184
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15/?
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126
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185
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Of Machines and Chaos

Summary:

Izuku, no last name, lived his life in this unforgiving society where those with quirks make all the rules.

By a stroke of luck he makes it into UA as a dual course student, makes friends, and meets some actual great teachers. Sadly society is not too happy about a quirkless person trying to become a pro hero in Japan.

Will Izuku push forward towards the path of heroism or does he crack under the unfairness?

Notes:

DISCLAIMER: I DO NOT OWN MY HERO ACADEMIA OR SONIC THE HEDGEHOG! MY HERO ACADEMIA WAS CREATED BY KOHEI HORIKOSHI AND OWNED BY FUNIMATION ENTERTAINMENT! SONIC THE HEDGEHOG WAS CREATED BY YUJI NAKA, NAOTO OHSHIMA, AND HIROKAZU YASUHARA! SONIC THE HEDGEHOG IS DISTRIBUTED AND OWNED BY SEGA!

THIS IS FOR ENTERTAINMENT PURPOSES ONLY!

Chapter 1: UA ENTRANCE EXAM

Chapter Text

It was a crisp spring morning, nearly a cloud in the sky. The cherry blossoms were starting to bloom as eager students rushed to take their entrance exams for their next stages of education. We find various students standing in front of massive gates, stretching their limbs as to prepare for strenuous activity. These young students were hero hopefuls, trying to gain admittance into U.A. Universities hero course. Many were wearing track suits, work out clothes that weren't too loose or fit around their bodies, and some were wearing some machines.

A Few children had certain appearances like longer limbs, animal features, or even mechanical parts. One such student had mufflers coming from their thighs, dressed in a blue track suits with dark blue hair and square framed glasses. He was a stiff student that followed the rules to the letter, respecting those that came before him, and never questioning authority. Right now he was keeping an eye on a particular student.

No, it was neither the frog girl nor the person with webbed arms and a mask. His parents and brother taught him better than to stare at those with mutation type quirks since they may either take offense or be self conscious regarding their appearance. It also wasn't the nervous girl near the gate, most likely trying to calm herself down. His eyes were trained on a curly green haired individual with dark roots. The boy had no obvious mutations, but he was clearly a rule breaker.

The engine boy marched towards the green haired adolescent. "Excuse me! I believe you are breaking the rules of this sacred exam."

The green haired teen turned towards the loud voice, as did a few other test takers. "I beg your pardon?"

"You are clearly violating the rules by using that equipment!", Engines yelled while chopping his arms like a robot. A few people chuckled at the action while others snickered at the foolish test taker being called out.

The green haired male tilted his head. "I'm afraid there's been a misunderstanding. I filled out all the necessary paperwork for my support items, even building them myself." The teen reached into his jacket pocket and pulled out some paper. "I have copies of the request forms during the physical portion of the exam."

The teen with mufflers looked over the forms, nothing that everything was in order. "My apologies! I assumed you were a delinquent trying to either cheat of sabotage the other examiners!", exclaimed mufflers as he bowed at a perfect ninety degree angle.

"No problem. This exam has everyone stressed out, tensions running high on trying to earn a spot in the most prestigious hero course in Japan if not the world." He reached his hand out as a sign of good fate. "I'm Izuku, it's a pleasure to meet you."

"A pleasure to meet you Izuku-san. My name is Iida Tenya!", replied mufflers as he shook Izuku's hand.

Izuku muttered, "Iida? Iida? Oh! You must be related to Pro Hero Ingenium. I must say it's quite an honor to meet a member of the famous Iida family, but I should have deduced that easily from those engines coming from your legs."

The two got into a small discuss regarding Ingenium, a reliable hero that employs more sidekicks than any hero in Japan, applying effective teamwork to track and capture various heroes. Many were now staring, but not at the two excitable teens. Rather they were staring at Izuku's support gear. Most brought some light armor or something to help with their quirks, but Izuku's took the whole cake factory.

He was sitting inside a floating metallic sphere with small red fins on the side, a glass visor at the front, and a small green circle just under that. If the floating contraption wasn't enough then the two standing beside it were equally shocking. Two different robots in stature and color stood by his side arms crossed. One was tall and lean with a gold color scheme while the other was short with a silver color scheme and slightly pudgy.

The silver one spoke up, "Doctor I don't mean to interrupt, but the exam is starting soon."

Izuku stopped his conversation. "Ah yes, thank you Bocoe."

The gold one talked next, "It's best we remained focused seeing as there are no countdowns in combat."

"Excellent observation and reasoning Decoe.", Izuku addressed the robots. "Iida-san meet my assistants Bocoe and Decoe, my greatest creations to date."

That shocked everyone around. A test takers their age created a floating vehicle and two robots?! He must have an amazing intelligence or technology quirk to create things that amazing. Iida congratulated him on creating them, referring to Decoe and Bocoe as things which offended them.

Bocoe responded, "How rude! We are sentient machines with feelings thank you!"

Decoe added, "How would you like it if we called you a cyborg with those mufflers coming from your legs?!"

Izuku waved his hands in a calming motion. "Now, now let's all calm down. I'm sure Iida-san didn't mean to offend you both." Izuku then turned to address not just Iida, but all test takers. "Listen up Decoe and Bocoe are sentient robots and are not to be targeted during the exam. Seeing as how they are registered as support items any harm inflicted on them will be classified as sabotaging a test takers. They are worth nothing except an immediate disqualification from the exam. Please be respectful of them and myself."

A random test taker asked, "What's to stop them from sabotaging us?"

Many agreed with that question about to hound the trio until an announcement came from the intercom. "AND START!!!" The massive gates opened as everyone just stood there. "WELL?! WHAT ARE YOU WAITING FOR?! THAT FLYING KID AND HIS ROBOTS ARE ALREADY AHEAD!"

It's true. As the examiners were standing there Izuku, Bocoe, and Decoe had made a mad dash past them, dismantling any robots that came their way. Everyone else rushed as soon as they got over their shock and followed. Iida had used the engines in his legs to give himself a speed boost not only to distance himself from other test takers, but to add some power to his kicks. A girl with rosy cheeks simply touched the robots, making them float, and smashing them onto the ground. The frog girl was clinging to the side of the building, scouting for robots to destroy and fellow test takers to save from harm. After all what is a hero if they don't save others.

Izuku fired a small beam from his floating machine while Bocoe and Decoe smashed robots, even taking a few out that tried and failed to sneak up on fellow examiners. Before long a strong rumbling overtook the fake city their physical test was taking place before a behemoth of metal smashed through a three story building. Many fled at the site to the zero pointer, but Izuku stopped once her heard a voice cry for help.

He turned to find a rosy cheeked girl pinned under rubble and what's worse? The hulking monstrosity of metal about to run her over! "Decoe! Bocoe! Help me free her and stop that behemoth!", screamed Izuku. Decoe and Bocoe both saluted and rushed to help free the young lady. Izuku flew up towards the zero pointer, blasted a hole big enough for him to enter, and started disconnecting wires. Good thing he wore his electrician gloves so he wouldn't get electrocuted.

The zero pointer started to spasm and spark, edging closer to the pinned girl. Bocoe and Decoe were able to lift the rubble from her ankle and gently lifted her up so as not to agitated the injury. As the zero pointers head tilted downwards something fell out of the hole. It was Izuku falling to the ground as his flier was smoking. Izuku mumbled, "Darn, overheated the laser function and now the controls won't respond!"

as he was falling to the ground a soft pain originated from his cheek. He suddenly floated just inches off the ground. "Release.", the rose cheeked girl stated before she barfed a rainbow. A RAINBOW! Was he hallucinating or was that a side effect of her quirk? Before long an elderly lady with a syringe cane walked around the testing site, handing out gummy candies as she congratulated all of them. She quickly healed the rosy cheeks girls ankle and walked over to Izuku.

She whacked him on the head with her cane. "What type of reckless plan was that?! You're lucky that the zero pointer didn't destroy another building as it lost control or accelerated and crushed that girl!"

"It was a calculated risk. Besides Bocoe and Decoe are tougher than they look."

The school nurse left after handing him a few gummy candies and another whack on the head for good measure. Honestly she could heal almost any physical injury with her quirk, but sadly stupidity wasn't on that list. Just look at Toshinori and how often her and Sorahiko tried to heal his recklessness.

All examiners left their testing sites, nervously waiting for when their letters would come next week with their results. many had a second plan with chosing general education, hoping to impress the hero course during the sports festival for entree next year. Some were smug thinking U.A. wouldn't be stupid enough to reject them and their perfect quirks. As Izuku was leaving someone spotted him, sending a heated glare his way.

"Deku!"

TO BE CONTINUED