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Ritsuka Fujimaru was a kind person. He made sure to humor the requests of all the servants that were contracted with him. Today, he had been going about his day as usual until he was approached by two of such servants. Which leads us into the current moment of the three of them standing on a mountain pass leading to a mountain in the distance.
“Sooo… Can one of you two explain what we are doing here?”
“Now now husband, you must have patience unless you want to spoil the surprise, isn't that right Ibaraki?~”
“Huh? Oh! Uh yes, be grateful that me and Shuten would grace you with as good of a surprise as we came up with! Now come on, let's go already!”
The two servants with him were none other than two very infamous oni residing in Chaldea, the Assassin class Shuten-douji, and the Berserker class Ibaraki-douji, both dressed in their usual clothes.
“Alright, can you at least tell me where we are?” Ritsuka tried hopefully, not really expecting to get an answer.
“Sure! Behold, for before you lie Mt. Oooe!” Ibaraki presented with her arm swinging in the direction of the mountain. Moments after, Ibaraki seemingly notices her slip up and covers her mouth with both her hands, at which Shuten can only shake her head in slight disappointment.
“Isn't that where your group used to reside?”
“That is correct, dear husband. We wanted to visit our old home and see if it has changed after our deaths, so we rayshifted to about a hundred years after our deaths. However, since you are such an important person to us as our Master, we wanted to visit it with you as a surprise for all you’ve done for us. Unfortunately, said surprise was just spoiled…” Shuten sends a glare towards Ibaraki, who in response attempts to start looking in the opposite direction and whistling with her hands behind her back.
“Well if that's all, I don't mind accompanying you two.” Ritsuka says with a shrug of his shoulders.
“See Shuten? I knew the human could not refuse such an offer from us!” Ibaraki says in joy over the thought of not having any consequences for her slip up.
“Yes yes, whatever you say Ibaraki. Well then, let us continue while the sun is still out, shall we?”
And so the trio continued their trek through forests and towards the mountain, until they finally reached a cave entrance. As if walking through the front door of their house (as it might as well have been) the two oni continued further into the cave, followed soon after by Ritsuka. Soon, they reached a drape that covered a part of the cave as if a door would, and after walking through it Ritsuka found himself in a spacious chamber of the cave that held some resemblance to a room. It was littered with pillows of various sizes here and there, as well as different kinds of furniture found in the average home of the time, most probably stolen from a village the oni raided in the past.
Soon, his attention was on his two servants yet again, now both sitting on a spot that had the floor completely covered in a bunch of pillows with Shuten beckoning him to come sit with them with sake in hand, to no one's surprise. As Ritsuka sat down, he found a gourd of sake being thrust into his face by the purple oni.
“No thanks.”
“Why not dear husband? This is a momentous moment worth celebrating. Come now, don't be the only one left sober~”
“What she said, Master! Come on, it's not everyday we get to be here, might as well celebrate a bit!” Yells out Ibaraki with a gourd of her own in hand, already chugging it like mad.
Another glance at the gourd in front of his face, and the captivating smell coming from it, Ritsuka caved with a sigh and took the gourd from Shuten’s hands, who beamed a very sweet smile as he opened the gourd.
“Just one gourd though, understood?”
Both the oni nodded in response, and so Ritsuka took the first gulp. As he expected, Ritsuka initially did not find himself liking the drink, but just as he was having second guesses, he noticed that the taste was getting a bit better in his mouth.
Meanwhile, as Shuten continued her own drinking, this did not stop her from observing him, or the small smirk she had. She noticed the two little bumps starting to grow on his forehead, and her smirk soon grew into a full smile as she observed the changes. It was working~.
Ritsuka, curious about the changing taste, lifted the gourd up for another gulp, but instead found himself taking two. It seemed like the taste was getting better and better the more he tasted it! More embarrassingly though, he could feel his pole below starting to harden, probably because of the presence of the two alluring oni with him. Maybe more of the drink will take his mind off it?
Too focused on these two distractions, Ritsuka failed to notice that something was going on with his body. The bumps soon grew further and started to harden, and his body started slowly getting a bit bigger. Too immersed in his problems, Ritsuka did not notice Shuten dropping all pretenses of drinking as she watched him with lust filled eyes, nor how Ibaraki looked with bated breath and with a line drool running down her chin.
“Shuten, Shuten! Can I go first?!” Ibaraki begged Shuten as she wiped the drool off her face, as Shuten only sighed at her partner.
“If you can't wait for the transformation to finish, then sure, go ahead. I’ll be waiting for the finished product~”
With glee and a beaming grin, Ibaraki turned back towards Ritsuka who had just finished his drink, and pounced at him, sending him to his back on the pillow covered floor with Ibaraki breathing heavily on top.
Before Ritsuka could ask what was going on, Ibaraki took a grip on his pants and tore them apart with fervor, revealing the slowly growing cock to her as she started to drool once again at the sight of it.
“Hey Iba, what-?!” Ritsuka tried to question, only for Ibaraki to shush him to silence. With the same power as before, Ibaraki took a grip of her own clothes and tore them off, to the surprise and arousement of her Master below her.
“Shush now Master, we’re going to have some fun ~. And dont deny you don't want this, I can see cock stiffening below me. So why don't we put it to good use~.” The oni said with a smug and horny grin.
Ritsuka, too embarrassed to admit he really was aroused by this, attempted to refute it, only for the excuse to die in his throat as Ibaraki dropped herself on his hard cock, causing both of them to moan in pleasure.
But Ibaraki gave him no room to breathe. She lifted herself only to drop herself down on Ritsuka again, producing another moan from the both of them as Ibaraki continued the cycle with growing speed. As the two kept moaning in their pleasure, Ritsuka’s changes did not stop. His figure gained a bit more bulk, his horns and nails became sharper, and the cock Ibaraki was repeatedly spearing herself on slowly kept growing, the sight of which causing Shuten to lick her lips, already awaiting for her turn.
But the transformation was not only happening on the outside. As Ibaraki kept bouncing up and down on Ritsuka in a daze of lust, he felt his arousal and lust grow even more. He found himself grabbing Ibaraki by the waist, the oni too distracted by her pleasure as he kept up her up and down motion. In a surge of strength, Ritsuka threw them both around on the pillows, putting Ibaraki below him and him above her, with his arms pinning hers above her head next to her horns.
“H-huh?” The lust dazed oni questioned, confused at the switch in position.
“You’re right, let's put it to good use. However, I’ll be taking control, okay?” Before the dazed Berserker could answer, Ritsuka started aggressively thrusting down on the yellow oni’s pussy, causing her to moan even louder as he kept grunting in the rhythm.
Taken by his lust, Ritsuka gazed down at the moaning girl below him, the arousing image causing him to hasten his thrusts as he grabbed hold of her breasts, increasing the pleasure the oni below him was experiencing.
“Ooh, Master! Keep fucking me as hard as you can! Fuck me every day and breed me like an animal! Ravage my womb with your cum like an oni would!”
His thrusts became stronger and faster with each word the oni yelled out, until Ibaraki reached her climax and came below him. The feeling of her cumming around his cock caused him to reach his climax as well as he shot ropes of cum into the girl, filling her womb completely.
Ritsuka withdrew his cock from Ibaraki, causing a whimper of disappointment from the girl as he stood up and looked down at her, the girl too exhausted to move, opting to instead bask in her lingering feelings of pleasure.
“Well done dear husband. I will admit, I did not expect for Ibaraki to end up below you, even less that she would be the one to stop from exhaustion.” Ritsuka turned around towards Shuten, the oni seemingly blushing from excitement with a lewd smile on her face. The smile seemingly grew at the sight of Ritsuka's cock, which he now noticed seemed to have grown somewhat. Usually, he would have been embarrassed over the thought of someone staring at his groin, but for some reason he seemed to have become more confident and assertive.
“It seems the changes are done~. Ooh, I can barely contain myself.” The oni sighed as she imagined a most likely dirty scenario in her head.
‘Changes?’ Confused, Ritsuka looked at a nearby mirror, and noticed that his groin was not the only place to have changed. His body was a bit bulkier, his nails were sharper, and most glaringly of all, he had a pair of horns, just like Ibaraki and Shuten.
“Have you noticed now, husband? Indeed, you are an oni now, just like the two of us.”
“How? Why?” Ritsuka asked, not as scared as he probably should have been. In fact, he felt better. Stronger, and most importantly, more hot-blooded. But still, he wanted answers, and so he would hear them.
“Did you not notice? You see we oni have seen our fair share of population problems, so our crew had an elixir that would turn any who drank it into an oni, just in case. It seems most of the sake gourds had been broken by animals or something else though, with the exception of one.”
“As for why? Well, don't you think it's a shame there are no oni anymore in the modern world? That mine and Ibaraki’s legacies were ended by that cow and her lot? Well, we thought ‘why not fix it’? And who better to help us than you, our Master~. I hope you don't mind being our consort, I’m sure that you would enjoy the position~” Thanks to Shuten’s enthralling words, as well as the implication behind her words, Ritsuka found his shaft begin to rise and harden. However, Ritsuka didn't mind this.The lust, now revealed to be brought on by his oni transformation, yearned for him to claim the oni woman before him, and he couldn't agree more.
“My my husband, are you already getting aroused by my body and words? I haven't even begun to explain how me and Ibaraki stole a couple of grails to incarnate ourselves so you could impregnate us with your seed, or how we destroyed Chaldea’s command room, making sure that no one would ever disturb us.” Shuten says with a smug and victorious grin, her words as well as her swinging hips causing his lust to rise even more. In a couple steps, she was standing right in front of him, caressing his chest with confidence and lust.
“Oh well, I was starting to get tired of waiting as well. How about we start? I’ll make sure you’ll enjoy-?!” But before she could finish talking, Ritsuka had pushed both of them down onto the pillows below. Before Shuten could grasp what was happening, Ritsuka had pinned her arms next to her and had torn what little clothes she still had on herself.
“Wh-?!” But Ritsuka did not give her a chance to talk, as the next moment he had rammed his cock down on the oni’s pussy, producing the most lewd moan ever moaned from Shuten’s lips. Before Shuten could get her bearings, Ritsuka was already slamming his cock down on her again, producing another lewd moan from her.
‘W-what i-is h-happening? W-wasn't I supposed to be on top-?!’ But before she could even finish her thought, another wave of pleasure assaulted her mind as Ritsuka rammed her yet again.
Shuten found herself losing her strength as Ritsuka kept ramming her, any plans to get herself back in control dissolving to pleasure before it could even be called a plan. Soon, she found herself giving up on such things, and fully immersed herself in the pleasure that was overpowering her.
“Nghh~! Please husband, I want your cum! I am your cum dumpster! A slut for your cock that needs your cum!”
The words sent Ritsuka over the edge as he came, painting Shuten’s womb in white as the woman under him reached her orgasm as well, basking in the feeling of being filled with cum.
Satisfied, Ritsuka rose to his feet and looked over his work. Shuten was completely ravaged, still dazed in pleasure with her blushing face giving away that the oni’s mind had broken from all the pleasure, the same being mirrored by Ibaraki a few meters away.
‘Shuten said something about having wrecked the command room, so does that mean we’re stuck here? What a shame…’ He looked back at the defeated forms of the two oni.
‘...That means I won't be able to get any more servants to have fun with. Oh well, I don't mind having just these two. I can't wait for what the future has in store…’
“Listen up you two! We’ll be reviving the oni and your gang just like you wanted to, but we’re making a few changes! From now on, I’ll be the leader of the gang, not you two, got it? The two of you will be my sluts instead. You two don't mind, right?” Two defeated voices try and answer, only to come out incoherent. However, Ritsuka can tell that after he had banged their brains out, that both of them have nothing against such changes as long as he would fuck them every now and then, not that he would need to be asked to.
“Great! So that's agreed upon then.” To Shuten’s surprise, she felt Ritsuka grab her by the leg and toss her next to Ibaraki, both still too exhausted as they gazed up with lust at Ritsuka standing over them, or more specifically the cock standing up long and hard.
“Now then, I am still a little hard though, so I hope the two of you aren't too drained yet.”
The two oni could do nothing but grin lewdly in excitement as Ritsuka dived on top of them and started fucking the both of them again at the same time.
That night, the sounds of monsters would echo around within the caves, as the returning oni celebrated their return in a way they did not plan to, but definitely did not complain about.