Fleeting Shadows (KNY x OC)

Prologue

Anyone who fights for humanity and for what is right...is a Demon Slayer.

Nezuko Kamado is the only known demon within the Demon Slayer Corps 

But what if...a newborn demon takes up the mantle of Hashira?

~°~°~°~

"Takashi-chan...?" Asks a man, not wanting to be the bearer of such heartbreaking news, as he walks carefully with a cup of water in hand towards a lone yet growing maple tree where a poised girl stands quietly and unmoving underneath.

Just as he could shorten the distance, the girl speaks, in a monotone but strained voice, clearly trying to choke back her grief as she keeps her back turned on him. "I know. I'd seen it coming anyway."

"I understand... if you want to grieve and so I should give you some space. But I just want to let you know that his last thoughts were of you and your safety," the man takes a few strides towards her to give her the cup. However, she still doesn't move and adds, her voice becoming more stern. "Do you think I should take up the blade?"

"What?"

"Do you think I should take up the blade?"

"I don't understand. You want to take his place?"

"Yes, Kyojuro," the girl finally turns around and looks up at him solidly with a newfound resolve, catching him off-guard at how swiftly she moved, "I'm usually not one for vengeance but my brother deserves justice, as do the countless that have died in the same manner."

Kyojuro sighs deeply as a sad smile ghosts on his lips, handing Sayomi the cup and shaking his head once. "Akatsuki would have killed me if I let you join the Corps. You are aware he joined to protect you out here. He always worried about your health-"

"I don't care about my health! Yes, I may be sickly but that's what training is for, right? To toughen up your constitution," Sayomi flails her arms up in annoyance but calms down to take a sip of the water, sniffling as she lowers her head slightly at the harsh reality of things, "I'm on my own now. My parents are gone. My brother is gone. I have no one but myself. The least I could do to honor Akatsuki's sacrifice is to protect myself and others." 

Tears begin streaming down her cheeks and it prompts Kyojuro to draw her in for an embrace. She sobs softly against his uniform as he caresses the back of her head. "You have spirit, Sayomi. But I can't guarantee your survival if you take up this task."

"I'm not letting my brother's efforts go to waste...and you bet I'm going to die avenging these souls." Sayomi pulls away and places the cup on one of the stones surrounding the tree, turning around to give a determined smile to Kyojuro as she wipes her eyes with her sleeves.

"I sure hope Akatsuki doesn't give me a beating when we meet in the next life," Kyojuro chuckles and rubs his forehead, pondering over things. He then turns his gaze to Sayomi and narrows his eyes at her intently. "I've noticed that you are pretty light on your feet and snappy with your movements despite looking-"

"Dead on some occasions? Yeah, I get that."

Kyojuro chuckles heartily again, his eyes crinkling with hope as he smiles warmly at her. Yet his expression gradually falls in worry for her decision. "That's an advantage but are you sure you want to do this?"

Sayomi crosses her arms and bites her lower lip, finally coming to terms with what she has to go through. "Yes. Besides, you're all I have now anyway so I would be officially under your hawk-like watch." Her lips slowly curve into a smile as she makes a subtle yet teasing reference to his wide eyes, causing Kyojuro to tut as he stifles a wide smile at that.

"And I swear," he pauses, his eyes lingering on the slightly gaunt girl a little longer before continuing, "that I'll do my best to be there for you."

Sayomi sniffles and beams through the pain of losing her brother. Grateful, nonetheless, to have someone like Kyojuro around. "I hope I don't hinder you from your current tasks."

"You won't," he steps closer to her and takes her hand in his boldly, reassuring her with a heartwarming gleam in his eyes as he declares enthusiastically,"we'll get stronger together, okay? You and me. We'll fight side by side! We could even become Pillars together!"

That was what he promised.

They had indeed trained, fought, and gotten stronger in the following years...

But what of the last?