A Hashira's Demon

Another Demon?! Pt 1

** RENGOKU'S POV **

Years have passed after the mansion, I still kept training my skills, keeping my thoughts distant for a little while. From what the Master has told me, YN did go to a mission, top secret to be exact, and was unable to return. Unsure as to why, I had to ensure that it wasn't for any other reason. When I always ask him:

"If it pleases you, sir, would you mind telling me why? I have to know!"

He'd always responds with:

"They're doing this for the sake of the Demon Slayer Corps. Once they return from this mission, everything will be alright."

It kept bugging me every moment of every day.
That was, until one day, as I was just returning from a mission.
My crow came to the door and cawed at me.

"You have a meeting to go to today! CAW!"
"I don't feel like going today. Give my regard to the master."
"It is required for you to go, Rengoku! CAW! Apparently, a demon has been found! One who has been travelling with a Demon Slayer corps member."

I stared in shock as the crow continued.
A demon? Found?!
Could it be YN?!
After all these years?!
I smiled and glanced at the crow.

"You should've started with that then! I am on my way to the mansion right now!"

The crow cawed as he left to announce it to the Master. As quick as the lightning hashira, I prepared myself and ran towards the mansion! It has to be YN! I know it has to be! I couldn't wait for us to talk again!! However, as I got there, something was off. I saw Shinobu and Giyuu standing there, not communicating to each other.

"What seems to be the problem my comrades?" I asked.
"Wow, Rengoku, it's been a while since we've seen you come through here, hasn't it?"
"I understand it was for a certain reason."
"Well, if you must know, we're here cause a new swordsman Tanjiro Kamado is to be put on trial for travelling with a demon."
"Travelling with? Isn't it seem a bit taboo for us to do such a thing?"
"Maybe, but what I'm more concerned is how Giyuu knew of this information without informing us at all."

I looked at Giyuu as he stared away for a moment.
It was never like him to ever do something like this before.
Unsure as to what it is, I had to talk to him privately.

"Shinobu, would you mind if I talk with him?"
"If you can get him to talk to you, he hasn't had a chance to say anything to me after we left Mt. Natagumo."

She started to leave, as I was left alone with Tomiyoka.

"Giyuu..." I started to speak.
"Don't." he interrupted, "It's none of your concern."
"I want to understand. Please, Tomiyoka."

He sighed and started to explain.

** TWO YEARS EARLIER, GIYUU'S POV **

I had just heard wind that a demon up in the snowy mountains had just struck a family dead up there in the dead of night. As fast as I could, I ran towards their hometown, trying to get there to rescue them. Unfortunately, I saw the incident: it was too late. I stared in shock of the accident, realizing that all of this was my fault. But as I was about to leave, I noticed a new set of tracks that weren't there when I got there. Examining the ground carefully, I then noticed an empty coal bag nearby that didn't have any signs of blood anywhere and a baby which had a small spot that wasn't covered in blood. Trying to use my senses, I followed its track and try to find the demon in question, thinking it still lurked around.

"Hang on, Nezuko!" a voice echoed in the distance, "Don't give in. You gotta hang on!"

Hearing his voice from a distance, I followed towards it, preparing the worst outcome.

"You gotta stay strong! Just hang on! PLEASE!!"

Thinking the demon got a hold of him after his shout, I ran towards them, jumped, and swung my sword towards the demon's neck. However, as the demon noticed, something trajected the attack and swung towards the boy's hair. Keeping my guard up, I noticed how he was protecting the demon in question.

"Why are you protecting it?"
"She's my sister!" he answered, "I was taking her to get help!"

Unsure whether or not to believe him, I went towards them and grabbed the demon from his grasp. He saw the outcome and prepared to move towards me.

"Don't move!" I ordered.

He obeyed as I held her tightly by her arms.

"My job is to slay every demon I find. Which means I have to decapitate your sister!"
"No, wait! She didn't do it! She would never harm a human!"
"Don't be fooled, she's turned because she was exposed to demon blood."
"But the one who killed my family wasn't Nezuko, it was someone else!"
"You're kidding right? If I didn't make it here on time, she would've eaten you right then."
"No, she wouldn't. She knows that I'm her big brother! Please don't kill her! I'll find a way to heal her!"
"She can't be healed. Once turned, no human has ever turned back."
"But there's a way: I know there is. Please! Just let her go!!"

Not hearing any of this, I prepared to strike her with my sword, but as I was about to do so, he bowed for mercy. Wasn't sure why, but it made me so angry. Why was this boy begging a life of a demon than granting me the mercy to kill his sister? Then it hit me. She's the only survivor of the attack. If the demon in question was in any way related to Muzan in any way, then he must have a way to reverse it. However, that boy can't get that resolve in this state.

"Don't grovel like that and give your enemies the chance to kill you!!" I yelled at him at rage. "All you're doing is making yourself vulnerable!! If it were even a little bit effective, your family would still be alive right now!! How can a weakling like you have any hope of finding a way to heal his sister or hunt down a demon?? Don't be ridiculous!! Now maybe the demons know a way to cure your sister. MAYBE!! But don't think for even a moment that any one of them will respect your wishes! Just like I have no respect for you! That's reality! All those mistakes you've done without attacking me are what led to her capture when I could've skewered the both of you and be done with it!"

As he continued to glance towards me, I knew my words had to have reached them somehow, but from his response, he didn't do anything. So I knew there was one other way for him to realize the outcome: to harm his sister.

"No!!" He cried.

His sister Nezuko cried in agony as my nichirin sword struck around her ribcage.

"DON'T YOU TOUCH HER!!" he roared, throwing the rock towards me.

Blocking its attack, the boy ran as fast as he could towards the hatchet and engaged an attack.
The winding snow engaged the attack as he threw the rock towards my head. Knowing where it was coming from, I dodged it while he straightway planned to attack me.

"You are a fool!" I growled angrily, knocking him out unconscious.

Lying on the snowy ground unconscious, I noticed that the boy's hands were completely barren with no hatchet in sight. As if by answered prayer, the hatchet was falling down towards my head, but turned to the side just in time. Surprised by his strategic moves, I knew this kid was serious, but he needed much training. Suddenly, as I continued to think, Nezuko freed herself from my grasp and went towards her brother. All of a sudden, after seeing Nezuko protecting her brother, I recalled hearing what Rengoku told me years ago:

"One day, Giyuu, you'll come across one: one who'll never eat or harm a human being for that matter. And when that happens, protect them with all your heart. Will you promise me that?"

"Rengoku... Looks like you were right about something for once. They need to be protected at all costs."