Omniscient Star || Kimetsu no Yaiba x OC

「Kamado」

"Why are you protecting that thing?" Giyu sharply asked.

"She's my sister!" the boy exclaimed. "She's my younger sister!"

The demon girl continued to growl as the boy struggled to hold her back. "N-Nezuko!" the boy choked out her name as he struggled to hold her back.

What a pitiful sight, Hiroyuki thought. I don't know what I would have done if Hayami was a demon...

"You call that thing your sister?" Giyu asked with a stoic face.

Hiroyuki winced. Master, you could've been at least more gentle with your words...

The boy vigorously sweatdropped as he took Giyu's words to heart. Giyu dashed forward, aiming to grab the demon girl called Nezuko out of the boy's arms. The boy hunched over, trying to protect Nezuko. But Giyu snatched her and drew back in a flash. So quick... Hiroyuki mentally took note of his moves.

Giyu's left hand was firmly holding both of Nezuko's arms behind her back as she writhed and growled, while his right hand clutched his sword.

"Nezuko!" the boy yelped.

"Don't move," Giyu firmly told him. The boy's eyes darted from Giyu to Nezuko, then spotting Hiroyuki up on the tree. Giyu, seeing this motion, called up to him without looking at him, "Hiroyuki, if you want to become a demon slayer, you'll have to be more stealthy and hide better."

"Right!" Hiroyuki replied.

A demon slayer? the boy thought. The wind blew the snow around them once again.

"My job is to slay demons," Giyu started. "Needless to say, I'm about to decapitate your sister."

Blunt as hell, Hiroyuki thought as his eye twitched at his master monotone voice.

"Hold on!" the boy exclaimed, despair cracking in his voice. "She hasn't killed anyone! Back at my house, there was another scent. One I had never smelled before! It probably belongs to the one who killed my family!"

Giyu's eyes narrowed. Kibutsuji Muzan, Hiroyuki frantically thought. That's the only one who could've killed this guy's family and turned his sister into a demon. Hiroyuki started to speak, but Giyu cut him off. "Hiroyuki," he said sharply, clearly not wanting to be interrupted.

"S-sorry," Hiroyuki muttered.

"It wasn't Nezuko...!" the boy continued. "I don't know what's going on with her now but... but still...!"

"It's quite simple," Giyu said calmly. "Her wounds were exposed to demon blood, so she turned into a demon. That's how man-eating demons multiply."

"Nezuko would never eat humans!" the boy yelled frustratingly.

"You've gotta be kidding," Giyu continued with a straight face. "You were about to be devoured just now."

"You're wrong! I'm going to turn Nezuko back into a human! I swear I'll cure her!"

Hiroyuki raised an eyebrow. Is that even possible?

"She can't be cured," his master said otherwise, "Once you turn into a demon, you can't go back to being a human."

"I'll search for a way! I'll find a solution. So please don't kill her!"

Hiroyuki's face softened. He recalled that night where he had to behead his father. He stared at the boy with an understanding look and sympathy. But there's nothing that you could do.

"I'll hunt down the one who slaughtered my family! I'll make everything right again! So please!" the boy shouted. But Giyu was already pointing the tip of his sword at Nezuko.