Reborn in demon slayer as an Uchiha

Father vs son

Last time in I was reborn in demon slayer as an Uchiha

He said all that while he was looking like I was an insignificant insect.
Veins started to appear on my face as I shouted out"I don't care if you consider me a disappointment, your words mean nothing to me especially now that you are a demon"

He look at me impressed before he said"Why don't you become a demon, you will become stronger than you could ever imagine, and you will finally stop living in the shadow of your brother Atoru"

"Imagine as a demon you will finally be able to beat that monster and be the older brother that protects his little brother that you wanted."He said extending his hands toward me.

"If I become a demon, I will no longer consider myself Atoru brother, I don't want to see his pained expression after he was forced to kill me,
I will be the older brother that he looks up to"I said getting into a stance.

Now we continue where we left off
"If you want to be so stubborn, then let me bury you today, "Shinjuro said as flame tattoos started to appear all over his body, while this was happening you could see actual flame emanating from his body.

Shinjuro gripped his sword as it turn into a flaming sword with blu flame covering the whole sword.
"Let's see what you are made of son," Shinjuro said before he rushed directly toward Rengoku.

Rengoku Pov.
I saw my dad running at me. I gripped my blade harder than I ever grip it in my life and rushed toward him. We clashed swords and his flaming sword was giving so much heat that it was hard to concentrate.

'I know that if we continue like this, he going to win because demons have unlimited stamina,' I thought gritting my teeth as I pushed him back

"So you did get stronger, hahaha," He said laughing, he look nothing like himself when he was human.
"Show me more, I can feel like you have more power, show it to me, "Shinjuro said before he rushed at me but this time before he reached me, he swung his sword at me and he was nowhere close to me but as soon  as the motion was over.

A huge pillar of fire was made, and it was coming toward me.I noticed that the fire burned everything it touches into ashes the floor was just getting disintegrated due to the immense heat that the fire contain.

"Stay focused" I heard a voice say behind me, my eyes instanly follow the voice but my head didn't follow the voice as fast as my eyes did, I saw my dad with a flaming sword and he was preparing a strike.

That would cut my head off and cauterize the wood at the same time.

The sound of a blade cutting through something echoes in the silent night, and droplets of blood fell on the floor.

"Huff, Huff, Huff" I huff, I was starting to get tired, I usually don't tire this easily
"What a shame, I only manage to cut your hair not your leg," Shinjuro said holding his son cut off hair.

"You are frankly boring so unless you have something that could mildly interest me, I will kill you," He said looking at me
I looked around before I noticed that the fire pillar was nowhere in sight, I immediately look at the destroyed path that the fire took but I heard that voice again.

"You don't need to worry about the fire, what you must worry about is me," He said pointing at himself.
"This is not my all," I said a yellowish aura started to cover my body

"You want to beat me with the technique that Atoru made for that weak bitch that can't cut a demon neck, don't make me laugh," Shinjuro said looking very disappointed but the disappointment soon turn into excitement as soon as he saw a green aura surround his son.

Shinjuro pov
My son pupil was still visible so he was just in the first level of both techniques but that doesn't matter, all that mattered now is that he could give me a decent fight.

I watched as his green and yellow aura neither mixed nor repel each other, they were both coexisting in harmony and complete peace.

'End this and do whatever you want with the body, just make sure the brat sees it. 'I heard a voice say in my mind, that voice had some sort of authority attached to it, I instantly realize who the owner of that voice was and so I answer

'Yes, master'.
'if he manages to escape the more injured he is, the more blood I will give you but you must make sure he dies if he survived' the voice boomed in my head and I knew what would happen to me if he survive.

So I got into my stance ready to kill my own son

Rengoku pov
I breathe in deeply filling my lung with four times the amount of oxygen it usually gets, I felt my mind get clearer, I felt all the doubts that I had left me and some sort of inhuman strength filled my body.

As soon as I exhale a crater was formed underneath me, it was not caused by my exhaling but because I realize more power exactly when I exhaled.

Veins started to appear on my face and my eyes went blink but my skin didn't turn red, I was using the second activation of the heavenly technique while also using the second gates in the 8 inner gates techniques.

"If power is what he wants then power he will get," I said before gripping my blade so hard, I didn't notice that I was bleeding and that my blade started to turn into a red blade.

"This better be your best because it no longer holds back, "Shinjuro said before he rushed at me

A/N Rengoku can't maintain his full power for long and if he goes into sure he might be a bit stronger but Shinjuro will outlast him, but on the other, if he stays where he is at right now he can fight till dawn.