|Protagonist| Kimetsu no Yaiba oneshots!

|Muzan x OC| Partners in Crime

Requested by: maverickhew01

A/N: Unedited

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The silence surrounding the household was disturbed by the front door suddenly slamming close. Concerned, Kishi Kibutsuji placed down her book and stared at the door of their master bedroom awaiting for her husband to arrived. And as expected, his footsteps came close and closer until he barges into the room while slamming the door harshly. His shoulders heaved as he panted in frustration. Muzan's eyebrows were knitted, fury and rage visible in his unnatural pink eyes. 

Her feet brought her body closer to him and held his cold hands, proceeding to squeeze it in comfort. "Is something wrong, dear?" she asked, concern in her hazel eyes. 

The scowl on his face intensified and avoided his wife's look. "A descendant of him lived." he answered, gritting his teeth yet squeezed her hands in return, careful not to hurt her with his strength. 

About exactly two years ago, Muzan came to the information about the existence of the descendants of his most despised man. Kishi remembered standing in cold snow while he did his business inside the small house of the family, their screams rang around the forest as the snow that glistened under the moonlight were tinted in dark red. She remembered looking up to the showering sky, devoid of emotions until her husband wrapped his arms around her waist and they left the scene. 

"Do you want me to send someone to deal with him?" She suggested, taking off his coat and hang it in closet, ready to call in a demon in a snap. 

He stared at the ground, the anger slowly dissipated. "I already sent the two to the young descendant. If they don't return by next evening, my presence will be known in the Corps." He trailed of and sat down at the edge of the soft bed in the middle of the room.

"Then I think it's time to call on a meeting soon if this draws on." Kishi states, the situation just became more difficult than they imagined as the ending draws near. As they marched closer towards the tip of the mountain where their domination awaited, nervousness bubbled in her stomach. She had trust in her husband's actions and plans yet deep in her mind she agitated in the idea of their enemies winning this battle. Their plans have the possibility to tip over and they fall to their death in just a span of 12 hours. 

Noticing the grim look in his wife's eyes, he grabbed her by the waist then proceeding to pull her down on the bed with him. "What's with the look dear?" he whispered in her ear as he pulls her close to him. "We still have time. The world will be ours." he reassured, placing a kiss on her forehead.

Deciding to ignore the burning thought for now, the Kibutsuji spent their morning sleeping and in embrace of each other's arms. For the next few months, they moved from town to town to avoid being pinpointed in one location by demon slayers while at the same time enjoying their time together as a couple.

Until one day they were sent an information that the Lower Moon Five and his makeshift family was exterminated by the demon slayers in Mountain Natagumo. Surprised and enraged by the news, the final decision that they once considered were decided.

Kishi paused her movements when she entered their bedroom. Her husband stood in front of a full body mirror, having a hard time styling his wavy pitch black hair. She stared at him or her, eyebrows knitted in suspicion. 

"Is that my kimono?" she pointed to the black floral clothing that he wore, remembering the moments she saw the set in her closet. 

"The meeting was called in a rush that I didn't get to buy my own." he shrugged, his patience were running thin on his hair than didn't seem to stay together in a bun. Kishi chuckled on his futile attempt at keeping his hair and grabbed the hair piece of gold and red. He sat down at the chair for her to reach his hair.

"Better not soil that okay?" she joked, expertly working on his hair. Though she was contemplating if that was truly a joke or a threat, even she don't know herself.

"You know what? I'll go with you." she stated cheerfully after finishing the masterpiece on her husbands hair. 

"No it's okay darling. I think I can handle everything, but I appreciate the concern." He smiled at her, thought the second he saw the expression on her face, it dropped. 

"Oh that wasn't a question. I've been stuck in this house for a month, I think I deserved to go out for a while don't you think?" Her eyebrows were raised, her arms folded over her chest as her hazel eyes challenged the piercing stare of her husband. And soon began their silent war using their eyes.

Whenever times like this, the stubbornness of his wife seems to take over. She never backs down whenever she thinks that her decisions were valid and wouldn't affect majorly in the business he does. Sighing in defeat, he nodded and went out of the room.

A big smile crept up in her face and quickly changed her clothes that matched the one that her husband wore. She tied her brown locks in a braid that rested on her right should then pinned with small flower pins in the middle of every braid.

The couple walked out of their new abode and in a snap they disappeared from the view.

The Lower Moon roamed around the fortress in confusion, the walls were either made in wood or tatami floors. They were spread in different locations. The fortress stretched into infinity, the stairs and floors placed in strange places, a sound of strumming surrounded the fortress. And suddenly, the remaining Lower Moons were gathered in one place at a single strum of the biwa. 

Their eyes searched the area until it stopped at the sight of a three women in front of them, one in particular stood in front of the two. The demon holding a biwa instrument sat, cross-legged at the left side while another woman in brown hair sat in the right side with a malevolent smile on her face. Her hazel eyes looking at the lower demons in delight. And to say that the Lower Moons were bemused, was an understatement. Just until the woman in black spoke with authority in her voice.

"Lower your heads and bow down." In a single order, every cell in their body obeyed and they hands laid flat on the ground as well as their heads in a bow. 

"P-please forgive us. Since you've assumed a different form and aura-" before a female Lower Moon finished speaking, she was cut off by Muzan's words. "-Who gave you permission to speak." 

"You can only answer when questioned."

As the time goes on that Muzan spoke, the four demons shook in fear on their knees as blood splattered on the floor. Kishi only watched, clearly enjoying the fear and death of those who didn't satisfy the order of her husband. She remained sitting down with a sinister smile on her face until one particular demon thought that the only option left to live was to flee. 

"How foolish.." Kishi whispered under her breath. And in a blink of an eye, her hands grabbed on tightly on the hair of the beheaded demon, its blood dripping down on the floors. Muzan sent a look of satisfaction on the actions of his wife, as for the remaining two, their emotions were in conflict. The other feared for his life as he suggested to be given more blood to be stronger, something that Muzan didn't like, in the end he also met his demise. As for the other one, he was interesting. The sadistic kind that sees delight on the agony of others, something that the Kibutsuji looked for in a loyal subject.

Time passed by and the couple returned to their home in contentment as they entered their room to change. "Now that the meeting's done, I'd like to get out of this uncomfortable clothes." he said in discomfort as he morphs into his male form, still wearing Kishi's kimono. An idea struck in her mind as a sly smile made its way to her lips.

"How about I take that off for you?" She offered suggestively, as she undid her own clothes.

"As you wish, my queen."

She was his queen, and he was the king and together they ruled the demons for generations as long as their bond existed. With the promise of forever that till death do they part.

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A/N: This sucked ass to write. I hope you enjoyed it! I had a hard time finding a perfect plot for this demon king. And the OC is just made on the spot, I don't have an OC. ;-;