Disclaimer I do not own Demon Slayer nor My Hero Academia
Just the plot and Original Characters
Narrator POV
1 month after the wedding, they didn't have a honeymoon
Izuku can be seen walking in the woods, his destination a old research lab that has long been abandoned. Why is he going there? Simple, Lowermoon 1 was spotted entering by their recon drones. Izuku this time will be working with the Flower and Flame hashira with the Flame hashira the only one taking their Tsuguko. Izuku has had minimal interaction with the two hashira even when they attend the same meetings now. They don't ignore him it's just that they never have something to talk about with Izuku and vice versa.
A couple minutes later Izuku saw the entrance of the lab but he also saw Asami Hashibira the Flower Hashira messing with a butterfly with a small smile as she leaned against a nearby tree. She was wearing the haori that all Flower Hashira have worn since the Taisho Era with a dark pink demon slayer uniform. She had semi long hair in a ponytail that turned blue at the tips, her ponytail was held in place by a blue butterfly pin. Her eyes were two different colors one green, one blue. She turned her head to Izuku as he arrived giving him a small smile.
"Hello Hashibira-san, I hope I'm not late." called out Izuku as he stopped a couple feet away from Asami. "Not at all Midoriya-san. I Just arrived and were still waiting for Todoroki-Sama and his Tsuguko." said Asami as she continued to mess with the butterfly before it flew away. Izuku nodded as he sat down on a rock not far from the entrance. A couple minutes later Izuku saw two figures walk up the hill towards the entrance. It was Enji Todoroki the Flame Hashira with his son/Tsuguko Toya Todoroki.
Enji Todoroki was wearing the Flame Hashira cloak with a dark blue uniform. He had sort spikey hair that was faded at the edge. He had an uninterested look on his face. Touya Todoroki was just wearing a pure white haori with the normal demon uniform, he looked angry as soon as he saw Izuku. He has white messy hair with the same eyes as his father. "Ah good morning Todoroki-san." called out Izuku with a grin but all he got was a grunt in response.
"Who the hell are you! This is an important mission we don't have time to waste with a weakling! Get the hell out of here and leave it to the strong!" snarled Touya at Izuku who looked like he could careless about what he was saying. "I think you should watch your son's mouth Todoroki-sama or he might lose a tongue talking to a Hashira like that." said Asami with a small frown directed at Touya who looked shocked at the news of Izuku being a Hashira. Enji gave Touya a glare that quickly shut up Touya who clenched his fist in frustration. "Well let's head inside to finish these Lower's" said Izuku as he jumped up from his rock and started walking towards the entrance followed by the rest.
"Do we know it's art at least." asked Touya with attitude towards Izuku who was almost at the door. "Nope." replied Izuku with a grin as he opened the door before it went away with the introduction of the smell of rotting flesh. That was enough evidence that demon lived there at least. The 1st and only floor on the surface was just a lobby with a elevator that obviously only went down. The slayers packed into the elevator and saw that there was a total of six floors with five underground. "Ok to make this faster let's have each one of us search a floor. Touya-san take the second floor, Hashibira-san take the third, Todoroki-san take the fourth and I'll handle the fifth. After we each search our floor we meet back inside the elevator and head to the sixth together. Good plan?" asked Izuku which everyone quickly nodded in response besides Touya who huffed in annoyance. "If you come across the moon call for backup and we'll come help." added Enji where everyone nodded in understanding.
They each were soon dropped off at their respective floor until no-one remained in the elevator.
With Izuku
The fifth floor looked like it used to be a quarantine ward or where they kept their patients with whatever illness. The smell was stronger and almost made Izuku gag but he continued walking. He didn't really find anything besides old notes on old weapons. Izuku knows when slayers grew in popularity and power that anything science related that didn't help destroy demons was scrapped a long time ago. Izuku continued walking until he turned a corner and came across two demons turned around revealing the kanji for Uppermoons in their eyes. 'Why do they feel so weak?'
With Enji
Enji's floor was a database with old computers that hadn't been turned on in decades. However, two Uppermoons also stood in front of him but they didn't feel right. 'Fakes?' thought Enji
With Asami
Asami's floor was a storage floor full of old documents and other items. However, to her inconvenience there was no demons and she was making her way to the elevator while grumbling to herself.
With Touya
Touya's floor looked like it used to hold animals with all the cages...hopefully. But currently he was fighting for his life as he got unlucky and fell upon a demon nest. "Flame Breathing: Seventh Form, Devouring Inferno" Touya leaped in the air and came down with a overhead strike killing several demons instantly along with the nest. Touya huffed in annoyance before walking back to the elevator.
With Izuku
"Your not an Uppermoon." said Izuku causing the demons to flinch but charges Izuku anyway. Izuku didn't even try as he cut both demons heads off and made his way to the elevator. 'Why were they pretending to be Uppermoons?' thought Izuku as he called the elevator.
With Enji
Enji said the same thing and killed them instantly and made his way to the elevator.
The group made it to the sixth floor and when the elevator doors opened they almost puked from the smell and were forced to cover their face with cloth to try and block it out. The sixth floor lobby led to a door which opened to what looked like a giant testing room. It didn't take long for demons to appear strength wise they were probably around lowermoon 3 level and they numbered in the hundreds. The group quickly started the fight trying to whittle down the numbers but more just kept coming.
"Sun Breathing: Third Form, Raging Sun"
"Flame Breathing: Fourth Form, Blooming Flame Undulation"
"Flower Breathing: Second Form, Honorable Shadow Plum"
"Flame Breathing: Second Form, Rising Scorching Sun"
They killed and killed but two would just replace each one they killed. Izuku stepped back to take a breather and he noticed a control room above them and Izuku the daring one jumped straight through it's wall and rolled to a ready position. Izuku found the Lowermoon and to say he was disgusted was a understatement. The moon was levitating from the ground looking down at the other slayers struggling against the demons. The moon's head was bigger then the rest of his body but eyes littered the head each with the kanji for lowermoon one. It was wearing a dirty lab coat that was smeared with old and new blood. "I'm impressed you noticed they usually don't like the one's down there. Here let me show you." said the moon as he snapped his fingers and Izuku saw all the demons from before never existed and the others were just fighting the air.
"The plan was for you guys to collapse from exhaustion and I kill you all after that but now your going to make me work for my meal. Well it's not like you'll be able to beat me anyway." said the Lowermoon with a sigh that annoyed Izuku. "As if!" yelled Izuku as he charged the moon 'Sun Brea-' Izuku didn't even make it halfway before he was stopped midair and then launched through two walls and slamming against the third one before collapsing to the ground in pain.
Blood dripped down Izuku's head along with blood from his mouth as he coughed. Izuku opened his eyes and saw he was in a doctor's office with his eyes traveling to the holes had just gone through. Izuku touched his chest and groaned in pain at contact. 'Three ribs broken and probably a bruised lung.' assessed Izuku as he struggled to stand up. For the first time in his life Izuku was heavily injured.
"Oh by the way the names Kokoro, be sure to remember that when your God asks who killed you." said the now named Kokoro as he hovered at the hole Izuku made. Izuku tried to stand but Kokoro waved his hand to the left causing Izuku to go through that wall then sliding and hitting a wall in a sitting position. Kokoro laughed as hovered closer to the even more injured Izuku. "You can't hit me. No matter how hard you try it won't happen." said Kokoro with a smug look as he stared down at the broken body of Izuku. Izuku laughed dryly as he tried to stand up with his sword. 'Sun Breathing: Firs-' Izuku was thrown to his right going through another wall then sliding and hitting his head knocking him out.
Kokoro hovered over the broken and unconscious body of Izuku with a smile than turning around and floating back to the control room. 'I'll kill him later. I want to watch those other slayers struggle a bit more.' thought Kokoro before he hovered back. A drone watched from a corner as it showed everything to HQ who was quickly sending reinforcements which were lead by Toshinori and Inko with Momo tagging along.
......
.......
Izuku opened his eyes and all he saw was darkness. He looked down and he was able to see himself pretty clearly but everything else was just darkness. "Is this a demon art or am I?" Izuku thought outloud as he got a little worried about his situation. "Your not dead, not yet at least" said a voice behind Izuku. Izuku turned around but got blinded by a sun until it slowly died down and revealed a old man with long white hair in a ponytail with a weird mark on his face. He wore a old style yellow kimono with a red haori. He also wore some strange earrings.
"Who are you?" asked Izuku as he stared at the old man. "My name is Yorichi." responded Yorichi with no emotion, Izuku sweat dropped a little as he waited for the man to continue but he didn't. "So why are you here and where even is here?" asked Izuku as he looked around in the darkness. "This is Limbo. Basically your between life and death this is how we are talking right now. I am here to see if you have what it takes to finish the Demon King. From what I've seen most likely not." said Yorichi as Izuku got a tickmark from his comment. "Well who are you to judge me?" asked an angry Izuku as Yorichi continued to maintain a neutral face.
"I am the first Breathing user and the First Sun Breathing user." said Yorichi which caused Izuku to freeze. "I failed as the first, the Second did even worse, the third cowered away and you fourth will most likely be the world's last chance to stop the Demon King. You must get stronger but first let's make sure you survive today at least. I'll give you my mark the rest is on you." said Yorichi as he grabbed Izuku's shoulder who grunted in pain as he head burned in pain. "Last word of advice, you must leave your emotions behind once again." said Yorichi as the darkness was soon over taken by light with Izuku quickly consumed by it.
Izuku's body laid still until his eyes shot open but they looked dead as if he wasn't completely there. Izuku stood up with no trouble and started walking towards the control room but besides his eyes the weirdest addition was the ugly mark that was on his right forehead. For some reason it looked like it was glowing and was similar to the old man's. Izuku continued to shuffle towards the control room with his blank look and the mark growing bigger and glowing brighter.
Kokoro can be seen watching the slayers struggle and close to exhaustion, while he smiles and giggles to himself. A piece of rubble fell at the entrance of the control room, one of Kokoro's eyes focused on it. 'A plant?' thought Kokoro as he felt and saw a plant standing there. Not paying it any mind Kokoro turned back to the struggle as the plant shuffles forward showing that Kokoro saw Izuku.
'Sun Breathing: First Form, Waltz Enhanced'
It was to late for Kokoro who turned his eyes but noticed the room turning upside down as Izuku passed by him cutting his head off. 'I died but how? That brat couldn't even make it two feet before.' thought Kokoro as his head hit the floor with his body slowly started dusting. Soon his surroundings became lighter as he remembered why he became a demon.
Kokoro was a scientist that tried to make advancements in both medicine and therapy. However, every time Kokoro would make a breakthrough or propose a project, it would get turned down and they always replied the same way. "How will this help us beat demons?" Kokoro fell into a depression that only alcohol could cure. One day they fired him since he wasn't making anything 'useful', as he was wallowing in anger in an alley a woman came up to him offering him a chance. Uppermoon 1 asked if he wanted to make a difference as she held up blood to him. Kokoro never looked back.
'I'm sorry Master ---------, Please forgive me.' said Kokoro in his mind
'Useless...' was the only reply he got as his body finally dusted away.
Asami, Enji and Touya looked around confused as they were broken out of the spell. Izuku can be seen standing there with a impassive look as a drone looked at him shocking the general public with the appearance of the new hashira along with his injured body and weird look. However, a woman at HQ watches with a small frown. Izuku was about to walk away until something crossed his mind.
'Breathe.' ordered a thought
Izuku suddenly collapsed as he gasped for air then started coughing badly with blood dripping through his hand that was covering his mouth and down his cheeks from his eyes. His mark disappeared as the others surrounded Izuku checking on him with Enji putting Izuku's shoulder on his back as he helped him out of the facility. If Izuku stayed in that form for even a second longer he would have passed his life limit and died.
As they exited the facility the group came across the back up which was Class 1A, Toshinori, Inko, Nejire, and Leiko. They all became shocked when they saw Izuku who looked like a mess with torn bloody clothes, him still coughing blood, and blood all over his face. None of them have ever seen what they considered a pillar of strength that injured. Izuku was put in an ambulance with Momo who tagged along as he was transported to the hospital.
Somewhere else
Nozomi is seen sitting with her children as they confirmed what was seen since Nozomi's eye is worst. "So Izuku unlocked the mark and the selfless state. That's great and terrible news." said Nozomi with a sad smile. Her kids looked confused at why it was bad. "Why is it bad mother?" asked her daughter with a questioning look.
"Izuku turns 22 next month."
End Chapter
Modern Era Secrets
Momo and Izuku were going to go to America for their honeymoon but Izuku go the call so they couldn't go.
Asami is the descendent of Aoi and Inosuke Hashibira. She retains Inosuke's anger during stressful moments. She also gets loud and brash when excited.
Ochaco is a considered a daughter by Asami but Ochaco refuses to acknowledge that because she believe she isn't worthy of that title.
A/N
I got nothing to say besides thanks for reading.
Next Chapter- Ch.17 Uppermoon 6