Hey so I am going to be doing one last story and yes this one is going to be a Highschool DxD story with a bit of Demon Slayer mixed in given who the main character is going to be along with his weapon and fighting style as we are going to see a bit of the Demon Slayer world in the start of this story but after what happens to the main character he is going to simply be in the Highschool DxD universe. Now then the main character is going to be an O.C. seeing as it is more fun for me to create and mod someone that I myself created instead of changing someone from the cannon into someone who they aren't and I have seen that happen many times before as some people make Issei not a pervert and strong right out of the gate or they do the same with a certain spiky blond haired moronic failure of a ninja and make him serious and strong so they are essentially an O.C. with the character's name slapped on him for no reason in the slightest other than the fact that we can. Now then my O.C. is going to be slightly older than Tanjiro by maybe a year or two I haven't decided yet but he will be almost or just as strong as Tanjiro was during the Swordsmith Village Arc. Now then for the breathing form I am going to be giving to my O.C. I was on the fence about making him one of the only few Sun Breathing users left as I believe it was stated that Muzan went on to kill all the remaining Sun Breathers or another established breathing style. After thinking it over I have decided that I am going to be giving my O.C. Sun Breathing and I the reason being is that I like all the attacks that come with it and as to how my O.C. will have the Sun Breathing forms is that I will have an ancestor to my O.C. be the only one out of Yoriichi's students to actually master Sun Breathing and he will pass it down to his family members. Now then for the pairing I am indeed going to be making it into a harem seeing as that is my thing now and yes I will list them off at the end of this chapter so get ready to see who is going to be in the harem. With that all out of the way it is time to do the thing that must be done before anyone can even start a story on this website. Disclaimer: I own nothing at all nor will I ever save for the O.C. I made for this story.
"Of all the demons I had to meet on this mission of mine, it just HAD to be an Upper Rank" a teenage boy thought bitterly.
The teenage boy in question is around the age of thirteen years of age with snow white hair that reaches down to his upper back with some of his bangs falling near his eyes, healthy pale skin color, and turquoise eye color. For clothing he is wearing the traditional demon slayer uniform, over that is a black and red checkered long sleeved cotton haori, and tucked into the belt loop of his bants is a weapon.
Said weapon is a Katana style sword with a royal blue hilt, black cloth is wrapped around the hilt giving it the traditional diamond like appearance, a rectangular shaped tsuba with four angular indentations with a black center and a royal blue border, an obsidian black blade, and a black sheath.
The creature standing in front of him was none other than Kokushibo the strongest member of the Twelve Kizuki which meant that the young man was not going to be getting out of this one. However there was a small chance that he might be able to take on the oldest of the Twelve Kizuki and manage to withdrawal and in form the Demon Slayer Corps of his ability so with that in mind the young man took a long breath to calm himself and unsheathed his blade while Kokushibo raised an eyebrow at the young man in front of him.
Sun Breathing Twelfth Form: Flame Dance
The young man preformed a two strike combo which started with a downward vertical slash leading into a horizontal slash right after.
Kokushibo jumped out of the way but slightly frowned as he knew those words very well as his now dead younger brother was the one who created such a technique which caused Kokushibo to speak.
"Tell me you name swordsman" Kokushibo asked firmly.
"My name is Ryuma Akatsuki a member of the Demon Slayer Corps" Ryuma said sternly.
Kokushibo blitzed forwards and unsheathed his sword with blinding speed and thought he struck Ryuma as a frown appeared on his face once again .
Sun Breathing Eleventh Form: Fake Rainbow
Ryuma preformed a high speed twist and rotation, creating an after image.
"If I didn't use the eleventh form my head would be on the ground right now" Ryuma thought seriously.
"Tell me something Ryuma Akatsuki, did a man named Yoriichi ever train anyone in your family" Kokushibo asked bluntly.
"According to my grandfather, an ancestor of mine was taught by someone with that name" Ryuma said seriously.
"Even to this day, you and your legacy continue to plague me" Kokushibo thought bitterly.
Kokushibo appeared behind Ryuma with a blank look on his face and swung his sword at Ryuma at blazing speeds with the teenage boy narrowly dodging it but Kokushibo was ready for this and responded with a powerful round house kick to Ryuma's left side. Ryuma hacked up a glob of blood as he was sent flying into a nearby forest before slamming into a tree making him let out a silent scream as blood was now dripping from the right side of his mouth and some was pooling around his left side.
"Damn that hurt more than I thought that it would, that bastard isn't even sweating yet" Ryuma thought bitterly.
Gathering up as much strength as he could Ryuma forced himself to stand on his feet as he gripped his sword and when he looked up he saw Kokushibo close to him.
Sun Breathing Eighth Form: Sunflower Thrust
Ryuma preformed a singular thrust utilizing the tip of his sword to strike at Kokushibo.
Kokushibo dodged once again before he grasped onto Ryuma's left arm and squeezed it as Ryuma left out a scream of pain as his arm was broken before slashing his sword against's Ryuma's chest getting another cry of pain from the Demon Slayer. Kokushibo seeing that Ryuma was losing a lot of blood just threw him up into the sky and pointed his sword at him.
"When I kill this child, I will finally prove to you that I was the better swordsman between the two of us brother" Kokushibo thought proudly.
As Ryuma was now falling from the sky he calmed himself and did his best to ignore the pain that his body was in and focused on the demon below him as he glared at the strongest of the Twelve Kizuki.
Sun Breathing Second Form: Clear Blue Sky
Ryuma spun and twisted his upper in a circular motion, releasing a 360 degree slash.
Kokushibo raised an eyebrow as a small smirk appeared on his face as he figured that this boy would just accept his fate but no, he was still fighting even in the condition that he was in at the moment.
Moon Breathing Second From: Pearl Flower Moongazing
Kokushibo preformed three crescent shaped slashes while releasing a multitude of crescent moon blades along with them.
Ryuma was screwed and he knew it as he was hit directly by Kokushibo's attack as he was pretty much blasted into a nearby river and was washed away with the clear water now being stained red with Ryuma's blood. Kokushibo watched his foe being washed away and knew that the teenage boy was extremely close to death, and he was tempted to fish the boy out and make him into a demon. Kokushibo thought that it would be a major blow to the Demon Slayer Corps to lose someone with the oldest and strongest breathing style to their enemy but by the time he finished his thought Ruyma was now sinking of the bottom of the river.
(With Ryuma)
"So explain to me why I agreed to do this for you" a female voice asked in wonder.
"I simply wish for this boy to get another chance at life is all" another female voice said honestly.
"I swear Kami, sometimes you do the strangest things ever but this one takes the cake" the female said bluntly.
"I understand Shinigami but this will be one of the last times that I do this" Kami said seriously.
"You do know that sending a Demon Slayer to that world will change a lot of things" Shinigami said firmly.
"I have faith that Ryuma-kun will be alright in his new world" Kami said honestly.
"Fine Kami, but this will be the very last time, I do something like this for you" Shinigami said seriously.
"Thank you Shinigami I promise you that I will stop doing this after I send him on his way" Kami said firmly.
"Very well then Kami, now get him healed and get him out of my domain" Shinigami said seriously.
Kami placed a finger on Ryuma's body and all his wounds began to heal and as this was happened she looked at the boy and as he was being healed Kami placed another finger on him. This time on his forehead as she implanted information about the new world that he was going to along with the knowledge of another attack for his Sun Breathing that a future Demon Slayer would create in the near future. Looking both ways Kami then planted her lips on Ryuma's forehead and channeled some of her power into him essentially making him a demigod which granted him youthful looks and the same extended lifespan of the supernatural beings of the world he was about to enter. With this done Kami opened a portal and gently placed Ryuma in it before it closed and she disappeared.
(Later)
In a city with people chatting happily, walking with their children and seeing them playing and a man with devil wings flying by. This is the Underworld and this is part of the city that is owned by the Gremory Clan.
But no one noticed on top of a building, is a figure wearing a black hooded cloak that is covering his facial features and said figure is watching over the city. Behind the hood is Ryuma though with slightly longer hair.
It has been a couple months since Ryuma appeared in this new world and right away the first thing Ryuma did was check his injuries and was shocked to see that they had completely healed. Another thing he checked was that his Nichirin Sword was still with him and to his relief it was as he would not be pleased if he lost his trusted companion but still was was surprised that his body was healed and he was moving after that beating he took from Kokushibo. Though part of him did wonder how he got to this area in the first place.
The first thing he did was get some information and learned that this place was called the Underworld and it was ruled by four people Falbium Asmodeus, Ajuka Beelzebub, Sirzechs Lucifer, and Serafall Leviathan. He also learned about the Old-Satan Faction and Anti-Satan Faction Civil War as the descendants of the original four devil kings wanted to follow in their ancestor's footsteps but some devils didn't. This sparked the civil war with the Anti-Satan Faction coming out on top but the devil king descendants and their followers disappeared without a trace.
Ryuma jumped down from the building and ended up in the alley before he walked out into the streets and started walking.
"The first thing I have to do is make it to the human world, but the problem is that I have no idea on how to do something like that" Ryuma thought firmly.
"I could try and find a weak point and see if there is a way to get to the human world that way" Ryuma thought seriously.
But suddenly his stomach began to grumble.
"First things first I need to get something to eat" Ryuma thought bluntly.
Ryuma started to walk forwards and noticed that someone had dropped money on the ground and as he picked it up he figured out that it would be enough to get him something to eat and so he made his way forwards.
(Another part of the city)
A thirteen year old girl with crimson hair, blue eyes, and cream colored skin is wearing a pink dress is walking around the city. This is Rias Gremory the younger sister of Sirzechs Lucifer and is the heiress of the Gremory Clan.
Her life is great but sometimes she wants to have a normal life but she has responsibilities, she studies and trains but a lot of the time she wants to play but she couldn't find anyone, except for her lone Peerage member named Akeno Himejima who is her Queen and best friend, but right now Akeno is busy with a request.
So she decided to go out with her older brother's wife Lucina Lucifuge.
She is the twin sister of Grayfia Lucifuge but the only difference being that her hair is slightly longer than the so called 'Strongest Queen' and she carrying her two year old son Milicas in her arms.
They went out to get some fresh air and walk around the city, however Rias slipped away from her sister in law as she wanted some time alone.
She is a tad upset as she just found out that she was going to be married to a member of the Phenex Clan and to make it worse it is the one member that she hates the most Riser Phenex. Her first meeting with him didn't go over well as he looked at her with lust and greed before claiming that if Rias turned out like her mother than he would be pleased to marry her. Rias of course tried to disagree with this but her parents had decided to completely ignore her and agreed with the Phenex Clan as they missed the looks that Riser was sending the Gremory Heiress.
"Stupid parents I don't want someone like him who is only after my name and body, I want a guy who is nice and understands me" Rias thought bitterly.
Unknown to her she isn't looking and she bumped into someone and both fell on the ground.
"Ow" Rias muttered in pain.
Then she looked at the person and is shocked to see it is a boy with a black cloak with his hood on but she can see his turquoise eyes.
The boy stood on his feet before looking at her.
"Here let me help you up" Ryuma said honestly.
Her cheeks gained a bit of color to them as she grabbed his hand.
"Thank you" Rias said softly but her blush was still there.
"My name is Ryuma it is nice to meet you" Ryuma said honestly.
Rias was about to introduce herself but then decided to keep her last name a secret just to avoid problems.
"I'm Rias it is nice to meet you Ryuma-kun" Rias said happily.
"Same to you" Ryuma said softly.
"Say Ryuma-kun are you new around here" Rias asked in wonder.
"Yeah I just got here today" Ryuma said firmly.
Then they both heard a growl from Ryuma's stomach which made him blush slightly while Rias giggled.
"You must be hungry, I know a good place to eat" Rias said honestly.
Rias then grabbed Ryuma's hand and started to walk away but unknown to Rias was that Ryuma was blushing slightly.
They then arrived at the restaurant, after they ate Ryuma was able to pay for everything even though Rias wanted to to pay for her own food but he said that it was a gentleman's job to pay for the lady's food, which made Rias blush as they made to a park.
"Say Ryuma-kun where are your parents" Rias asked in wonder.
"They're gone" Ryuma said in a somber tone.
"I'm sorry, I didn't mean to bring it up" Rias said in a sad tone.
"It's okay, I know that they are with me in spirit and will always love me" Ryuma said happily.
Suddenly an idea came to Rias as she looked at her new friend.
"Maybe you can come with me, my family is nice and they don't have a problem if you stay at our home" Rias said honestly.
"Sorry but I can't do that" Ryuma said honestly.
"But why" Rias asked in wonder.
"Let's just say that it is complicated for now" Ryuma said honestly.
This made her sad but before she could say something another voice was heard.
"RIAS" a female voice yelled in the distance.
They turned to see a woman with silver hair and a grey dress holding a two year old baby.
"I got to go" Rias said sadly.
"Don't worry we'll see each other soon" Ryuma said honestly.
Rias smiled and ran over to Lucy.
"Here I am Lucy" Rias said happily.
Lucy turned to see her sister in law and smiled.
"There you are I was so worried about you when you suddenly disappeared" Lucy said firmly.
"Sorry" Rias said sadly.
"Well I'm glad that you're okay" Lucy said happily.
She nodded and realized something.
"Wait can we take my new friend with us" Rias asked happily.
"Who's your friend" Lucy asked in a quizzical manor.
"Right the-" Rias was about to say.
She turned to see Ryuma was now gone.
"He was right there" Rias said honestly.
"Are you sure" Lucy asked in wonder.
"He was there but now he's not" Rias said sadly.
"I'm sure you will meet him again" Lucy said truthfully.
Then a teasing smirk appeared on her face.
"Also you said he, so that means it's a boy" Lucy said in a teasing tone.
This got Rias a blush a lot.
"Well, well it looks like my sister in law has a crush on this boy, but what makes him so special to make her blush like this" Lucy thought with a smile on her face.
As Lucy and Rias walk away little baby Milicas is looking up into a tree and saw Ryuma.
"Hard to believe that I met and befriended the heiress of the Gremory Clan if the wife of the current Lucifer came to get her, now I really have to keep my promise to her" Ryuma thought honestly.
(Later at Gremory Mansion)
When Rias and Lucy returned to the Gremory Mansion they were greeted by Rias's parents and to Rias's relief Lucy didn't tell her parents about her little disappearing act. During the meal both her parents and older brother looked at Rias in wonder as she is unusually silent but they chalked it up to her thinking about her impending marriage to they let her be. We then cut to Rias in her room while looking at the moon while thinking about a certain boy that she met earlier.
"Is something on you mind Rias-chan" a female voice asked in wonder.
Rias turned around to see her best friend and queen Akeno Himejima.
"There is nothing Akeno-chan" Rias said in a neutral tone.
Akeno didn't but that for a second.
"Rias-chan I know something is on your mind, is it a boy" Akeno asked with a smile.
That made her blush a bit but Akeno smiled.
"Oh my, you have to tell me about him" Akeno said happily.
Rias shot Akeno a glare.
"Why" Rias asked with a serious look.
"So that I can get to know him as well and even have a bit of 'fun' with him" Akeno said in a slight lustful manner.
All Akeno got in return was a pillow to the face.
"Listen here Akeno-chan, Ryuma-kun isn't a toy" Rias said firmly.
"Oh so that's his name, thank you" Akeno said happily.
Rias glared at her best friend before she calmed down and started to take off her clothes as she has a nasty habit of sleeping in pretty much nothing with Akeno following soon after.
"Akeno-chan I have decided tomorrow after school I'm going to find him and convince him to come with us" Rias said firmly.
"Why" Akeno asked in a confused tone.
"Because he is a orphan Akeno-chan, he is all alone and has no one to look after him" Rias said honestly.
This made Akeno sad as she to in a way was an orphan.
"Alright then how about we go together" Akeno said with a smile.
"You just want to meet him" Rias said bluntly.
Akeno giggled at her best friend before the two of them went to sleep.
(Different Location)
In a lone alley way three people are talking.
"You two know your role correct" a blond male asked with a smirk.
"Yeah we know, but make sure that you keep your end of the deal brat" a male said with a firm and serious tone.
"Riser will honor his word if you two do your part" Riser Phenex said seriously.
This is Riser Phenex the fiancé of Rias Gremory.
The two nodded which made Riser smirk before he turned around and walked away.
"Those two were easy, when I end up killing them then Rias-chan will have to accept me as her fiancé and prove my power of the Phenex Clan" Riser thought smugly.
When he left the two looked at one another and smiled.
"Well that was easy, that fool doesn't even know our plans isn't that right Rago" the first male said with a smirk.
Rago looked to be in his mid thirties with black hair reaching down to his upper back, brown eyes, and is wearing some old armor with a sword strapped to his back.
"Indeed Kazu" Rago said gleefully.
The other man Kazu looks nearly identical to Rago but instead of black hair Kazu's hair is brown that is slightly shorter than his brother and is wearing a long cape and has two gauntlets on his wrists.
"We will finally have revenge on that bastard Sirzechs, and what better way than to kill his beloved baby sister" Rago said with a sadistic smirk on his face.
"Indeed brother the Demon Brothers will have their revenge" Kazu said gleefully.
They then disappeared.
Finally done with this one and now onto updates.
P.S. The Demon Brothers are O.C. villains for this prologue arc.
Harem for Ryuma: Rias Gremory, Akeno Himejima, Koneko Toujou, Kuroka, Ravle Phenex, Rossweisse, Female Issei Hyoudou, Irina Shidou, Xenovia Quatra, Asia Argento, Gabriel, Serafall Leviathan