#yandere kokushibo | tinandabin (2025)

( yandere Kokushibo x daki type fem reader )

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This is a one-shot for @caramelllfox ( this girl has too many creative ideas ) AND LOOK AT THE FANARTS SHE MADE OF READER LIKE DAMN.

All the credits of this AU to @caramelllfox. Just a quick explanation, this reader has powers similar to Daki's! :)

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Humming you continued to browse through the various displays of hairpins, wonderful kimonos and sandals. Smiling slightly to yourself as you thought about just how naive and stupid humans can be, there was a demon disguised as an Oiran in between them, yet they carelessly paid her no mind. Rather, they were worshipping her for her beauty. Half of them don't even know about the existence of demons, how stupid.

Meanwhile in the infinity castle, Uppermoon one, Kokushibo has been given a mission to survey the red-light district to find a particular ointment that Master Muzan needs. Luckily for him, he wanted to check up on [Name] because beautiful women were going missing in the red-light district, where [Name] is residing. She is a fine piece of art. Sometimes it makes him jealous to know that she is in the red-light district, full of lustful men and arrogant women. He could give her a much better home.

Reaching the red-light district, Kokushibo in his human form looked for the ointment with not much interest. Well, that was until he heard a familiar voice coming from inside the crowd. Hurriedly he pushed himself into the crowd, careful to not display his inhumane strength he looked at the argument...going on between two women. Sighing, he thought what a waste of time...

Just as he was about turn around and leave, looking forward to seeing [Name] again the argument going between the two women began again, this time more heated.

"Haah, you," Scoffing, you pointed at her and continued, "and more gorgeous than me..?" Who does she think she is? No one even knows who she is. All she was looking was for an argument. You really are pretty. You aren't an Oiran for no reason.

Scowling, the women retorted back with, "Obviously! Are you blind?" As she then went on about a rant about who is more gorgeous while Kokushibo stood in between the crowd, not really surprised you are in another argument. He was 100% ready to go full bonkers and chop up the women then and there but you would be...angry. At him. I mean, he isn't supposed to help you. You are far better than him! You could handle this on your own, you don't need someone else's help. Even if you did, your [B/N] is there to help. Ain't no way you are gonna accept help from that six-eyed freak.

'Hey, hey...[Name] how about I come out there and kill that ugly woman..?' Your brother's voice resonated in your mind. 'No. I will do it myself.' You replied, still glaring at the women when you sensed Uppermoon one's presence.

Glancing around, you looked for where could uppermoon one be when you spotted him. It wasn't that difficult, he is pretty tall and could be easily spotted. Seeing him, you frowned and quickly announced, "Let this woman take that hairpin, I will pay." Smiling mockingly in her direction, chuckling you said, "I pity you. So blind of the truth." And left with Kokushibo looking at your retreating back.

Stomping away and shooing the men that were following you, you entered an empty alleyway reeking of rats and rotten food. As soon as you were completely alone, your [B/N] came out of your back and stretched.

"What do I do now, Onii-chan?" Worriedly you asked your brother. You had always depended on him, you didn't trust anyone else other than him. He knew you like the back of his hand and you always sought his guidance in even the smallest of tasks. You may have put up a bold act back there, but deep inside, all there was a child.

"Don't worry...You can easily kill her." Grumbling your brother patted your head, consoling you unaware of the six eyes watching them both.

Kokushibo never liked [B/N]. You always depended on him so much and trusted him too much for his liking. He could easily protect you and grant any of your wishes, then tell him why? Why do you always choose [B/N] over him? And to add the cherry on top, you hated him. It was like you just disliked his entire existence as soon as you knew about him. I mean, he did stalk you a lot, but he never got caught. He rarely ever interacted with you, yet you hated him with a burning passion.

"Ne ne, [Name], you can kill that woman right?" [B/N] questioned you with a smile on his face and still hesitating a bit you answered, "Yes-Yes! Only one beauty can exist here after all...Not like that woman is pretty at all!"

Ruffling your hair, [B/N] grinned and told, "Your Onii-chan is always here for you, okay?"

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"This woman tastes the worse, Onii-chan!" Throwing the human leg away and pretending to barf, you complained as [B/N] was just sitting around and examining the mess you made.

"Does she really?" Sniffing the leg, tf your brother also followed your action of pretending to barf and throwing the whole body away. "You did a good job, [Name]," Smirking, [B/N] went back in your body but not before praising you.

Feeling 700 times better, you were about to shift into your human form when you sensed another demon's presence. It wasn't your brother. No. It felt off. Very off. It reeked of dark intents, lust, greed, desire, craving, obsession, and most of it all which was the most evident envy.

You couldn't properly recognise who it was until you turned around. Uppermoon one. Who would have thought that his presence would be so terrifying? You had only seen him from far away, which you were grateful for but now that you...are in his presence, his terrifying presence....you don't have a good feeling.

Kokushibo had stalked you more than enough to know everything about you, from your personality to your breathing pattern. ICANT All he now wants is one answer. Rest all wouldn't need your opinion.

"What do you want, you freak?" Angry by his mere presence, you sneered at him. You are sure he knows that you hate him, then why does he even try to interact with you? You could never stand his presence, let alone like him.

"I will leave...you alone after you...answer one of my questions...." His six eyes stayed on your figure, unblinking. He didn't plan to do anything bad in his opinion yet.

Laughing, you pointed a finger at him with wide unbelieving eyes and in disbelief said, "Do you....really think I will answer your question?" What a fool he is to think that! You have no gain in giving him answers, and you highly doubt he would leave you alone even after you answer his question.

A small frown made its way on his lips as he expertly ignored what you just said and continued, "Why do you....hate me..?" He never interacted with you, as said before. So what made you hate him so much? You both had never met except for a few times you saw him out of the blue.

From all he knew, you are no uppermoon. Nor do you seem to care that he is one either, which was a bit surprising for him but he was only all the more amused. But now, this act of yours, of you, hating him is getting pretty...annoying.

You were stunned to silence. Did he not know why you hated him? This all must be a joke, another play he is doing to amuse himself. Obviously. There is no way he couldn't know that. "Don't act like you don't know the reason." Glaring at him, you blatantly refused to answer. It's not like you were embarrassed to tell the reason, but you think, no this is a play for his own enjoyment.

He didn't reply and kept on expectantly looking at you, waiting patiently for an answer.

"Do you...seriously don't know?"

"No."

"That sucks for you, buddy. Bye."

"Master Muzan told me everything." Glancing at your feet, you mumbled out. [B/N] watched with interest, you had also not told him the reason why you hated uppermoon one. Not like he asked. You felt a bit sad when you thought about it. Would your brother also do the same?

"I hate you because you chose power over your own sibling." A simple sentence. A simple sentence that connected all the puzzles together.

"I may be just like you, but I won't sink that low for power. Master Muzan told me everything. My Onii-chan would never do that.." You were hesitating a bit to say that both upper moon one and [B/N] noticed that. You aren't sure...you think your brother hasn't even told you the full story. Of how you both became demons. You were surprised and excited when he told you he remembers your past and Master Muzan was suspicious of him...You don't think he even told you the truth of how you became demons..

Kokushibo was stunned. What would Master Muzan even gain from telling you his past? And to make you hate him. Was that your sole reason? Or is there something else? He saw you hesitated to say that your brother won't sink that low. You aren't even sure of it yourself. He was also somewhat...angry. No, he was very angry. He doesn't like to be reminded of his past. Of his failures as a human. Of how much Yoriichi is better. Such a stupid reason to hate him and remind him of his past, he thought as he unsheathed his sword when he sensed your brother's presence.

In terms of strength, Kokushibo respects his strength. But not the person. No, he isn't worthy of such power. Even so, he isn't more powerful than him. If he wanted, he could easily kill your brother. It doesn't seem like he can, or at least question Master Muzan about this. So what better way than to kill your brother and make you forget about him?

Before Kokushibo could kill your brother, he summoned his blood demon art sickles and threw them at him, which Kokushibo effectively dodged.

"Blood demon art: Flying Blood Sickles," [B/N] mumbled as a barrage of blood blades headed toward's Kokushibo. His attack accomplished nothing, as Kokushibo evaded each one of them, which didn't really surprise the skinny demon. [B/N] commanded his attack to turn, revealing its auto-tracking nature. Kokushibo deflected the attack again, not seeming like he is gonna be making a move anytime soon. He continued to relentlessly avoid each of his attacks without breaking a sweat.

This went on for a while as [B/N] continued to attack Kokushibo who has done nothing but dodge until now. He was just about to, just, he was so near to cutting off your brother's neck when your belts appeared at the sides of your brother's neck and Kokushibo tried to cut them but for some reason, they weren't. It was like they got hardened. Like a rock. Now, a rock isn't difficult to cut through for Kokushibo but he still couldn't. It was annoying to say the least.

While on your side, it was really difficult to keep your belts so hard that even uppermoon one couldn't cut through them, it was sucking all your energy. But if you stopped that then surely Kokushibo would decapitate your brother...But he can't die like that! Even your neck needs to be decapitated. But what if, what if, Kokushibo decapitates your brother and then...grabs you and runs away? You don't want to seem that entitled but you won't put it past Kokushibo.

It was getting difficult to keep your belts hardened, both Kokushibo and [B/N] noticed and it was a surprise that [B/N] hadn't helped you yet. The sweat around your forehead and your gritted teeth were enough of an indicator that [B/N] needs to step in or else both of you would die here. More so, him. As soon as you blinked the whole fighting stance changed as your brother's eye appeared on your forehead enhancing your abilities and both of you engaged in battle with uppermoon one. It's a surprise you both have been alive for this long.

Kokushibo was purposefully avoiding using his blood demon art because it would maybe even kill you. He doesn't really care what happens to your brother. I mean, he is over here actively trying to kill him. Nevermind he isn't even trying. Rather, he is just playing around. I told ya, this is like a game for him. Sad. 😔

"You both will...lose anyways...just surrender..." Kokushibo's deep voice spoke up amid the broken district. Everything was destroyed, broken debris crumbling as trees fell over with dead humans laying around. It was a sight to see for demons. The sun was nowhere near to coming out.

"As if!" You scoffed at him before using your blood demon art, "Eight Layered Obi Slash!" You created 8 long-ranged sashes to cut down Kokushibo from afar. He didn't move. Not at all. He kept standing there, waiting for your attack to come and in his eyes, it was very slow. As soon as ot reached it, it didn't even scratch his body. Not even a fucking paper cut.

This went on for some time, with both of you and your brother attacking Kokushibo who is just standing there like a statute. Though Kokushibo would never admit it, [B/N]'s poison did work. A bit. It was like a paper cut. Kokushibo had forgotten his mission long ago, Master Muzan had strictly given him a deadline to come back within 2 hours and it had been 1 second longer than 2 hours.

And so the next second you all found yourself in the infinity castle, with Master Muzan glaring at you three as all of you immediately bowed, intimidated.

"Kokushibo, what is this? I gave you a task to complete and here you were, fooling around." Muzan questioned with a deadly glare on his face as veins popped around his forehead, accusingly pointing at him as he scoffed at you and [B/N].

"I apologise....Muzan-sama....I had gotten carried away...I shall accept...whatever punishment you think...fits this...." Kokushibo apologised for his actions and declared to take any punishment which Master Muzan thinks will fit this.

Humming, Muzan questioned Kokushibo, "Any..?"

Kokushibo knew that this was not good. Because now let's be honest, when Muzan says any then y'all know Satan is coming to pick you up.

Backing down from his word is now not possible. Because one, Muzan won't give a fuck whether he agrees or not. If he were to decline what he said then Muzan would just make it a worse more of a punishment. Two, he loves his pride as much as he loves reader so he is not gonna be backing down. Now, he isn't gonna ask him how bad can it be, because it is gonna be bad. And Muzan can also read the minds of his demons and would 100% make it more worse if Kokushibo were to think that.

"Yes...Muzan-sama..." Kokushibo answered and as soon as he said that, Muzan's smirk grew like he was gonna do something bad. Lmao, what did you expect?

Before you knew it, Master Muzan was holding your throat as he grinned at Kokushibo who was a bit surprised and...angered. Yet he didn't act upon it because it would do nothing.

"Then surely, you won't mind it if I kill her?" Mockingly smiling at Kokushibo, he 'asked' him if he would mind you being dead, which Kokushibo hesitantly denied by shaking his head.

Chuckling, Muzan looked at [B/N] who didn't look alarmed or even, frightened in any sense and said, "It seems as to our deal is now over."

Your world went silent.

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After your death, Kokushibo didn't care much. He would complete his missions on time, get stronger in his free time and go on with his life as he used to. Except for one thing. You were still always on his mind. He had thought that maybe when you aren't alive, he will forget about you soon enough.

He never did.

There hadn't been a day where he hasn't thought about you. Even though all the memories with you weren't at all-loving, it was something.

He was confused and angered when you died. He was confused as to what kind of deal did your brother and Master Muzan had? Why wasn't your brother affected by your death at all? And he was angry that you died. So easily. You died because of him. Because he hadn't completed his task on time. Because of such a small mistake. That's what he thought at first. But when he started unravelling what kind of deal did Master Muzan and [B/N] had, he knew it wasn't his fault.

From the start, you were blessed. Blessed with beauty, born into a rich family in the red-light district. A beautiful baby girl was born to be an Oiran. Having servants doting on her, with her parents added affection to having a comfortable bed to sleep on. From gorgeous kimonos to stunning jewellery. She really did have the dream life of many.

Many suitors tried to get her hand-in-marriage but none were deemed as the one who deserved you by your parents. They were proud of you the day you were even born. I mean, who wouldn't be? As soon as you were born everyone was stunned to silence of how can a newborn be this, this, glorious at one sight?

From that day on your parents begin to shield you from the world, always saying no one deserved you. A blessing from the Gods. They treated you normally, is what they told you. You were the talk of the district.

Every time you went out with your parents you would always wonder why do people live in such...ugly conditions? And why do other parents allow their kids to play with other children? That's bad! They aren't protecting them.

Soon enough, your parents had adopted a kid. Before he could even interact with you, he was given 2 years of lessons on proper etiquette, hygiene, clothes, everything. They really thought you were a blessing from the Gods and deserved the best of the best.

The first time [B/N] interacted with you, he was a bit jealous of you. You were born in such luxury and had everything you wanted ready at your feet. While he would be getting abused. He was even sure your parents only adopted him to show a good face to the public. Of how good they are.

Soon enough, that jealousy turned into pity as he saw how you got treated. Like a deity. You didn't even have a normal childhood, but to say you didn't enjoy the treatment you got was an understatement.

You became obsessed with attention from then on. If someone weren't paying attention to you, you would throw a bratty tantrum and all the attention would be on you no matter the situation. Someone's birthday? Just throw a cheery smile and you got your way. Someone funeral? Just cry a little pretty and there came the tissues.

You had your own enemies who wanted to kill you. It was no surprise many were jealous of you. Each one of them were taken care of. [B/N] wasn't really adopted by your parents. He clearly remembers the day when they told him that. They had taken him in and trained him to protect you and take care of anyone who even dare look at you the wrong way.

They didn't tell him that at first because his child-like brain couldn't take it in properly at first. He was annoyed when they told him that. But soon enough he got used to getting his hands dirty and protecting you.

One day, an assassination attempt almost got to you and killed you. Almost. The demon was sent by Muzan who was quite interested in this life of yours. He had heard a lot about this blessing of a child and came to see this for himself. He had his reasons. A few of them could be that he was curious, will this brother of yours be able to protect you? From a man-eating demon? Who could easily overpower some kids? He was pleasantly surprised when your brother was able to kill the demon.

He saw potential in you. And your brother. You seemed to have a lot of talent to be a powerful uppermoon yet you couldn't be bothered enough to care about it because you had everything you wanted ready at your feet.

And so when you were about to take your last breath, he proposed the idea of you both becoming demons. [B/N] accepted without hesitation, because in his life there was only one goal. Protect you.

Even after you both became demons, he continued to protect you. Not because he wanted to, all because he was assigned to. Not by Muzan. No, your parents. He had a really strong sense of following what he was told to do. That's the way he was raised. Muzan used that to his advantage and manipulated him into thinking that if your parents would die, then he will be able to do what he wants. He won't need to protect you. For Muzan, it was rather easy to make [B/N] work according to his will.

Originally, Muzan was gonna help you become stronger and then use you as a pawn. But then his uppermoon one started expressing interest in you. Of course, he decided to use that to his will and indirectly threatened to kill you if he were to not do what he wanted. Kokushibo could easily understand the underlying threat.

Seeing he had 3 powerful demons under a leash, he decided to add more drama for his own amusement. And so he told you Kokushibo's past life. You seemed to value loyalty a lot. How could you like a pest like him if he couldn't even stay by his brother's side? Your onii-chan would never do that.

And then he made a deal with [B/N]. He values principles. He still clearly remembers all the rules he was taught before being able to interact with you. One of the most evident was, 'Never lay a hand upon any of the family members, unless they are a threat to [Name].'He couldn't find any reason for your parents being a threat to you. And so he left them be. It's been just a few years since you became a demon.

And so Muzan struck a deal with [B/N]. 'You will keep uppermoon one away from [Name] and in return, you will no longer be related to the [Last Name] family.'

And with Kokushibo being threatened that he will kill you if he doesn't do what he wants, you hating Kokushibo and [B/N] keeping uppermoon one away from you. It was going just as he wanted.

​​​​​​

He continued manipulating all of you, some were aware some weren't.​​​​​​

All these memories kept replaying in Kokushibo's mind as his life flashed before his eyes. The memories with you, the day he fought you, the day you got killed, when he found out about your past. How less did he get to know you in this life? He thought as he felt his neck get decapitated. Why didn't he ever get to hold you? He thought as he felt his body crumble. Would anything have changed if he had done Master Muzan's task on time? He thought as he closed his eyes. Are you also happy? He thought when he heard the demon slayers announce their victory against uppermoon one. Would you have ever loved him if it were for different circumstances? He thought as his ashes blew away in the wind, his wishes long forgotten. The wishes he hoped would come true now all but remembered. The tree's leaves fell, as one of his wishes was whispered into the moonless night. He hopes you both get to meet again and this time under proper circumstances.

He loved you.

But he was too late.

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Accismus, a form of irony in which a person feigns indifference to or pretends to refuse something he or she desires.