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In School Regression

Summary:

Genya wakes up feeling little but tried to power through it and go to school, which does not end well for him.

Notes:

(See the end of the work for notes.)

Work Text:

Genya had woken up that morning feeling fuzzy. A type of fuzz he had felt many times before. Normally he wouldn’t mind, he would find his brother and let him know what was going on and things would be fine. 

 

But today wasn’t like that, today he had school and no time to give into the fuzzy feelings and just be little.

 

And as much as he hated the idea, he felt confident that he could get through the day, and if he still felt this way he could give into being little when he got home. 

 

“Genya, wake up! I’m leaving in twenty minutes and if you aren’t ready I’m leaving without you,” Sanemi called through Genya’s door. 

 

“I’m awake,” Genya replied, doing his best to sound big, “just gettin’ dressed.”

 

A task easier said than done as Genya found himself struggling to get his uniform on. He almost fell over while putting on his pants, struggled with the buttons on his shirt, and couldn’t get his tie straight no matter how hard he tried.

 

“Genya!” Sanemi called again.

 

Genya stared at himself in the mirror, his uniform was a disaster and Sanemi was getting mad at him. And Genya would rather his uniform be sloppy than to deal with his brother yelling at him when he felt small. 

 

Genya left his room and went to the kitchen where Sanemi had set out a simple breakfast of just toast for Genya.

 

“Why does your uniform look like that,” Sanemi instantly commented upon seeing his brother.

 

Genya just shrugged as he sat down.

 

“Genya, you’re not a baby, you should be able to dress yourself properly,” Sanemi warned, sitting up from his seat at the table. “Turn around to face me.”  

 

“Sorry,” Genya mumbled, turning to follow Sanemi’s directions.

 

Sanemi then crouched down and started fixing Genya’s shirt and tie. After he had straightened out Genya’s uniform Sanemi looked his little brother in the eye for a few seconds.

 

“You feeling okay?” Sanemi asked, the harsh tone he had before replaced by something much softer.  

 

Genya nodded, “just tired,” he told Sanemi. 

 

“If you say so,” Sanemi sighed as he stood back up, “hurry up and eat or we’ll be late.”

 

Genya nodded again and ate his breakfast.

 

Genya was not an overly chatty person. He would engage in conversation when he had to but he was also perfectly content sitting in silence. 

 

But when he is little, Genya speaks even less. Sometimes he just found it hard to string words together and preferred to communicate in non-verbal ways. 

 

The drive to the school was quiet. Genya didn’t want to talk and instead entertained himself by playing with the zipper on his school bag, and Sanemi never tried to start a conversation either. 

 

Eventually Sanemi pulled into the facility parking lot. Genya struggled to get his seatbelt undone; eventually Sanemi reached over and released it for him.

 

“You sure you’re okay, bud?” Sanemi asked.

 

The simple utterance of the word bud could have been enough to make Genya slip fully, but he managed to fight it off and shook his head, “I’m fine, just an off day.” 

 

Sanemi frowned, and Genya wondered if his brother was starting to catch on. 


He could only imagine Sanemi being annoyed that Genya had regressed on a school day. And when he was little the last thing Genya ever wanted to do was upset his brother. 

 

“If that changes, come get me,” Sanemi told Genya before he got out of the car.


Luckily Genya didn’t struggle with the door and managed to get it open without incident. 

 

“I’ll see you in math period,” Sanemi told Genya as they reached the high school building.

 

“See you in math,” Genya responded. 

 

He stood, watching his brother walk down the hall to the teachers office. Part of him hated watching his brother leave, he wanted to chase after him but Genya knew he was at school and when he was at school he had to be big and independent. 

 

After Sanemi was out of sight, Genya went to his classroom and sat at his desk. Genya was normally one of the first people in his class, simply because he always arrived with Sanemi who liked to be at the academy early. Genya didn’t mind this, he liked the quiet mornings. 

 

But eventually his classmates would start arriving, and as they did they would group together and start chatting. Normally this never bothered Genya, but this morning, when he was little, the sounds were overstimulating. He covered his ears and tried to make himself as small as possible. He felt tears prick his eyes, he didn’t want to start crying over something as simple as a loud classroom.

 

Once class began, Genya realized this was going to be harder than he expected. He was struggling to focus as his eyes kept wandering to the window. And worse, most of what was being said was confusing. The words were too big and said in ways that Genya just couldn’t wrap his head around. He was trying his best but nothing was making sense to him. 

 

“Shinazugawa,” Gyomei, called his name.

 

“Y-yeah,” Genya answered, straightening up.

 

“Are you okay? You seem very distracted this morning.”

 

“Oh, I’m fine, just tired,” Genya dismissed, reusing the lie he had told his brother this morning.

 

Gyomei didn’t respond to Genya's excuse, just gave him a look and went back to teaching.

 

Genya in turn tried even harder to pay attention in class, the task slowly becoming harder. And by lunch time he was actually tired.



All he wanted to do was find Sanemi, hug him, and cry. He was overwhelmed and overstimulated and exhausted. Everything he hates being when he’s little.



“Hey Genya,” Tanjiro greeted as he ran up to Genya’s side.

 

Genya smiled and offered Tanjiro a small “hey.”

 

“Are you okay?” Tanjiro asked.

 

“Tired,” Genya repeated, however this time it wasn’t an excuse as he actually was tired.

 

“If you aren’t feeling well maybe you should talk to your brother, I don’t think he’d want you at school if you’re sick.”

 

“‘M not sick,” Genya told Tanjiro, “just tired.” 

 

Tanjiro clearly didn’t believe Genya as he reached up and placed the back of his hand on Genya’s forehead, then frowned. 

 

“Well you don’t have a fever,” Tanjiro muttered.

 

“Told you, just tired.”

 

Tanjiro still seemed worried about Genya, and Genya wasn't sure how he felt about that. He really didn’t want Tanjiro, or any of his friends for that matter, to learn about his age regression. He knew if they found out they would think he was weird and wouldn’t want to be his friend anymore. 

 

“The others are probably waiting for us in the cafeteria," Tanjiro remarked, grabbing Genya’s hand, “we shouldn’t keep them waiting.”

 

Genya was not prepared to deal with his other friends. Tanjiro was nice, he was always calm and soft. Genya liked that. But Inosuke and Zenitsu were a whole different story.

 

Honestly, Genya wouldn’t really say they were his friends, at least not by choice. 

 

Inosuke and Zenitsu were both loud, almost always loud. Genya could handle it on normal days, but this was not a normal day. And as he sat at the table he found himself gripping his pants tightly just trying to keep himself together.

 

“Genya?” Tanjiro said softly.

 

“”M fine,” Genya mumbled, “everything is just loud.” 

 

“Inosuke, Zenitsu, quiet down a bit, you’re upsetting Genya,” Tanjiro warned his other friends.

 

Genya wanted to disappear. As grateful as he was to Tanjiro, the sudden attention on him made him more nervous. 

 

“Sorry,” Genya quickly muttered.

 

Lunch did not go well for Genya. For starters he didn’t want to eat, he was never a fan of eating when he was little. And Tanjiro didn’t like that Genya wasn’t eating and forced him to eat just a bit. Inosuke was only quiet for about ten minutes before he started up again.

 

And Genya felt like was about to burst into tears. He tried his best to stay calm. He wasn’t about to cry at lunch because he was a bit overstimulated.  

 

Genya was almost happy as the bell rang, until he remembered his class after lunch was math, and he would have to see his brother.

 

At this point, Genya could confidently say he was no longer big. He was little and he was stuck at school. 

 

And he knew seeing his brother could easily be the straw that breaks the camels back and cause him to fully slip. 

 

When he entered the classroom Sanemi was already at the front of the class. Genya looked down at the floor trying to avoid making eye contact with his brother, knowing full well once he did he would break. 

 

Even when he reached his desk Genya kept his gaze on his books, only looking up to see what Sanemi was writing on the board. But at this point the numbers were just confusing lines. 

 

Genya was starting to regret coming to school. 

 

Slowly Genya started to tune out Sanemi’s lecture, not on purpose, but he just couldn’t focus anymore. His uniform was too tight, the seat at his desk was too hard, and the chalk hitting the chalk board was too loud. 

 

He placed his head on his desk. He knew his brother hated when students did that but it was the only thing he could do to tune out everything going on around him.

 

But suddenly the constant sound of Sanemi’s voice stopped and the room went silent. Genya looked up expecting his brother to be upset at him, but instead he noticed his classmates staring at him, some whispering to each other. This was followed by Genya realising the classroom was not silent, and there was the sound of something wet hitting the floor. 

 

Then Genya made the worst realisation of his life. The sound was coming from him and he had just wet himself in front of his classmates. He’d wet himself in front of his classmates during math class with his brother watching.

 

Genya couldn’t hold back his tears anymore as he finally broke down, into loud and ugly sobs.

 

“Everyone out of class,” Sanemi demanded, “go out to the field or something.”

 

Genya could only just process the sounds of his classmates leaving the room until it was just him and his brother.

 

Sanemi knelt by Genya’s desk avoiding the large puddle Genya had made.

 

“Genya,” Sanemi’s voice was soft, “how old are you bud?”

Genya just shook his head, he didn’t know how old he was, all he knew was that he was little and wet and embarrassed.

 

“You just feeling little?” Sanemi asked.

 

Genya nodded, still bawling. 

 

“Why didn’t you tell me this morning?”

 

“Didn’t… want to… make Nemi… mad,” Genya choked out between large sobs.

 

“Oh Gen,” Sanemi grabbed one of Genya’s hands and squeezed it, “I’ll never be mad at you for being little.”

 

“Not mad at me?” Genya mumbled trying to wipe away some of his tears with his free hand. 

 

“I’m not mad at you bub.”

“Even though I had ‘n accident?” 


“I’m upset but not mad.” 

 

Sanemi let go of Genya’s hand and stood up, causing the little to whine.

 

“It’s okay,” Sanemi said softly, “Are your gym pants clean?”

 

Genya nodded.

 

“How about we get you changed into those okay?” 

 

Genya nodded again.

 

“Think you can do it on your own?”

This time Genya shook his head. He found it hard enough to get dressed this morning, now that he had fully slipped he wouldn’t be able to get changed on his own.

 

“Okay, I’ll help you get cleaned up bud,” Sanemi told Genya, helping his brother from his chair.

 

Genya cringed as he heard the sound of his accident hitting the floor, then he buried his face into the crook of Sanemi’s neck.

 

Sanemi rubbed Genya’s back, “it’s okay, I’ll clean it up once we get you changed.”

 

Sanemi grabbed Genya’s hand then led him to the back of the room where the students' gym clothes were kept. He grabbed Genya’s clothes, then began leading Genya to the staff washroom. 

 

Students weren’t supposed to go in, but it was a single stall and was more spacious.


Lucky for them both there were no other students in the hallway to see the aftermath of Genya’s accident. 

 

Once inside the washroom Sanemi closed and locked the door then put the toilet seat lid down. 

 

“Okay, first we’re going to get you out of your wet pants,” Sanemi told Genya, making sure the little knew exactly what was going on.

 

Genya nodded, bringing the sleeve of his shirt to his mouth.

 

Sanemi undid Genya’s belt then helped his brother shimmy out of his wet pants, then his wet boxers. Sanemi hadn’t even thought about the fact Genya didn’t have underwear to change into, but he was planning on taking his brother home as soon as everything was cleaned up. 

 

“Can you sit on the toilet for me, Genya?” Sanemi asked.

 

Genya nodded and did as he was told. 

 

Sanemi then grabbed some paper towel and got it wet at the sink, then handed it to Genya.

 

“Can you wipe yourself down?”

Genya hesitantly grabbed the wet paper towel from his brother and with some effort wiped down his legs.

 

“Good job, Gen,” Sanemi praised his brother, tossing the paper towel into the trash bin.

 

Sanemi grabbed Genya’s gym pants then turned to his brother, “okay lets get you into these.” 


Genya nodded, stood up and went over to Sanemi, who then helped him step into the pants then pulled them up.

 

“There we go,” Sanemi said, “now we’re going to the teachers office.”

 

Genya nodded once more, and Sanemi knew it was highly unlikely he would get any words out of his brother any time soon. But that was okay, Sanemi knew Genya was quiet when he was little like this.

 

Sanemi grabbed Genya’s hand and made his way down to the teachers office, careful to not go too fast so Genya could keep up.

 

Sanemi opened the door to the room and looked around, seeing the only other teacher in the room was Uzui.

 

“Uzui,” Sanemi called in his usual harsh tone.

 

“Oh Sanemi,” Uzui turned to greet the other teacher, “all your students are outside.”

 

“I sent them outside,” Sanemi quickly explained, “I need to watch Genya for ten minutes.”

 

Uzui looked to see Genya standing behind Sanemi, clearly trying to hide but it wasn’t working out as Genya was already taller than his older brother.

 

“Sure,” Uzui responded.

 

“Great,” Sanemi then turned to Genya where his tone of voice changed again, “Kay bud, I need to stay with Tengen for a bit.”

 

Genya nodded very slowly, he didn’t actually want his brother to leave him. But he knew he also had to listen to his brother.

 

“I won’t be long,” Sanemi reassured as he sat Genya at his desk. 

 

Sanemi then left the room and for a bit Genya was okay. But slowly he started feeling alone, and he wasn’t sure how long ten minutes was and he missed his brother and tears started to fall down his cheeks again.

 

“Genya?” Tengen got closer to the little, “you okay kid?”

Genya shook his head, “Nemi” he muttered.

 

“Your brother will be back soon,” Tengen comforted Genya.

 

Genya sniffled and rubbed at his cheeks with his shirt sleeve. 

 

Sanemi had gone to the cleaning closet and grabbed some disinfectant and paper towels, then went back to the empty classroom. He went over to Genya's desk then began cleaning up the mess.

 

It wasn’t the first time he had cleaned up an accident and it most likely was not going to be his last either.

 

Once everything was cleaned up, Sanemi returned to the washroom and washed his hands, before again going back to the classroom and gathering up Genya’s books and bag. He didn’t expect his brother to get any homework done tonight, but it was still a good idea for him to bring the stuff home.

 

When Sanemi returned to the teacher’s office, he was greeted by a very upset Genya.

 

“What the hell happened?” Sanemi asked as he made his way over to his brother and Uzui.

 

Upon seeing his brother Genya immediately started doing grabby hands at him.

 

“Kid just missed you,” Uzui explained, “I tried to calm him down but he was pretty upset.”

 

Sanemi sighed, then helped his brother to his feet, “makes sense. He’s had a rough day.”

“I bet,” Uzui agreed, “he seems pretty small right now.”

 

“Very,” Sanemi confirmed, “I’m taking him home. Get someone to cover the rest of my lessons.”

“Wait, what?” Uzui stood up. 

 

“I’m taking my brother home,” Sanemi repeated.

 

“Who do you expect to cover your lessons?” 

 

Sanemi shrugged, “figure it out.” 

 

Before Uzui could protest, Sanemi was out of the office and the door was closed. 

 

“‘m s’rry,” Genya mumbled.


“You don’t need to say sorry Gen,” Sanemi told his brother softly, “stuff like this happens.”

 

Genya didn’t reply and kept following his brother to the car. Once they got to the car Sanemi opened the door for Genya then helped his brother get buckled in before going to the driver side and getting into the car himself.

 

In the short time it took Sanemi to walk around the car his brother had brought his sleeve to his mouth and was chewing on it again. Normally Sanemi would discourage such behavior but he didn’t have any of Genya’s chewelry or pacifiers on him.

 

The drive back to their apartment was as quiet as the drive to school in the morning, with Genya absentmindedly staring out the window watching the other cars drive by. 

 

When they reached the apartment, Sanemi got himself and Genya out of the car and started towards their apartment.

 

“Think you can make it up the stairs, bub?” Sanemi asked his brother.

 

Genya hesitated then slowly nodded.

 

“It’s okay if you can’t, I can carry you.”

 

“Please,” Genya whispered. 

 

Sanemi smiled then lifted his brother up. It was always a tad awkward carrying Genya around, mostly due to how tall he was. But Sanemi had found a way to make it work, plus he would rather his brother be carried awkwardly up the stairs than have him trip and get hurt.

 

Once they had made it back into the apartment Sanemi carried Genya to his room.

 

“First let’s get you into something more comfortable, okay?”

Genya went back to responding with a simple nod.

 

“Want to pick something out or should Nemi?” Sanemi asked.

 

Genya with his sleeve again in his mouth pointed to his brother.

 

Sanemi smiled, and pulled Genya’s sleeve from his mouth causing his brother to whine, but before it could get any worse Sanemi grabbed one of Genya’spacifiers from the top of his dresser and put it in Genya’s mouth.

 

“Much better than your sleeve.” 

 

Genya was content with his pacifier and watched as his brother went into his dresser and pulled out a pair of sweat pants and boxers, followed by him going to the closet and pulling out one of Genya’s favorite hoodies.

 

Sanemi wasn’t sure if he should put his brother into some protector or not. The worst case would be Genya having another accident, which wouldn’t be as bad since they were back at home. He decided it wasn’t that important.

 

With the new change of clothes Sanemi began helping Genya out of his uniform and then into the sweat pants and hoodie.

 

“There we go,” Sanemi smiled, welcoming Genya up, “all comfy?”

Genya nodded then nuzzled into Sanemi’s neck.


As Sanemi was leaving Genya’s room he grabbed Genya’s Bingo plush off his bed and brought it with them to the kitchen. Sanemi put his brother on the counter then gave him Bingo, which caused the little to make small happy sounds around the pacifier. 

 

While Genya was preoccupied with Bingo, Sanemi grabbed one of Genya’s sippy cups from the cupboard that he then filled with apple juice. He again grabbed Genya and brought him to the couch, carefully placing him down.

 

Sanemi sat beside Genya and gave him his sippy cup which he happily took. 

 

“How about we watch some Bluey,” Sanemi suggested, grabbing the remote for the TV.

 

Genya nodded his head enthusiastically, Bluey being his favorite show to watch when he’s little.

 

Sanemi turned on the TV, then logged on to Disney+ and turned Bluey on for Genya.

 

Genya made more happy noises and held his Bingo plushie tight as the Bluey theme song began playing.

 

Sanemi couldn’t help but smile, both of their early lives were rough due to their father, and even after he was gone things didn’t get any easier. Now Sanemi was able to offer his brother a safe space for him to be a child again. Even if it could be annoying and stressful dealing with his brother when he was regressed, small moments like this made it worth it.

 

As Bluey started, Sanemi reached over and pulled Genya into a hug, kissing his brother's forehead. 

 

Genya just giggled in repose which just made Sanem smile more. There were no signs that just a couple hours ago Genya was upset and at school.

 

Sanemi combed his fingers through his brother's hair, Genya pressing himself close as he did so. Eventually Genya had his head in Sanemi’s lap, his knees close to his chest and Bingo held tight. Sanemi would easily call this a perfect moment, and one he wishes could last forever. 

 

“Nemi,” Genya said around his pacifier.

 

“Yeah bud?”

 

Genya turned looking up at Sanemi, “love you, Nemi.”

 

Sanemi smiled more than he ever thought he could, “love you too Gen"

Notes:

AHHHH it's been a while since I have written an age regression fic. Recently the Demon Slayer fixation has gotten me and Genya is my favorite character, so I said.... let him be little and here we are. I actually have more ideas for one shots like this that I will be working on. I already have one finished actually it just needs to be beta read.

So I hope you like this because there will be more eventually!

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