One of a kind (Nezuko x Male Reader.)

Promise

"Remember, (YN), the Niko style I'm teaching you is for protecting sexy girls like your grandfather used to do back in his glorious days."

The elder man in front of you cheered as he flexed his battle-hardened muscles. He was towering, almost two meters tall and his well built body is witness of a thousand battles. Wrapped in his favorite black Gi.

In the ground, with aching muscles and a gallon of sweat, a younger (YN) (LN) tried his best to not die.

Even at such age, you had to train body and mind. Your grandfather was in charge of that as the head of the dojo and the strongest Niko style user alive. He was restless and his routines are like a hell, even for a kid he shows no mercy.

"You're the next heir of the Niko style, you can't be slacking, what do the rest of the students will say?"

True. At least thirty students come everyday to the dojo to train different martial arts, your family is known for being masters of many disciplines. From boxing to judo, karate and jujitsu. But only a few students are able to gain knowledge of the fearsome style your family has guarded throughout years.

"You know, those siblings who recently entered the dojo, they have potential, what was their name again... um"

"Ume-chan and Gyutaru-kun" you reminded while struggling to get on your feet.

"Yes, yes, those two, you have to try harder if you want to impress the cute girl, don't you want to have a cute girlfriend like her?"

"Sh-shut up geezer!" You answered flustered by his comment.

It was true that the little girl who recently started her classes was cute. But, you didn't care about that at all. For now, that's it.

"I just learned this stupid style because you pushed me to. I hate working out." You complied with a pout.

"No, no, listen up. The Niko style is like every other martial art, created for the weak to protect themselves from the strong. Always remember that" he shuffled your messy hair with a smile on his face. Every time he smiled, he looked ten years younger "And also remember (YN), you always have to protect a girl."

It was the only thing you remember and well. Also you remembered aside of that, was the smell of burning flesh and fat. A massive blaze and the screams of help...

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White and clean. A pale light in his field of vision, pain and doubt swirled inside of you.

What is this place?

*beep* *beep*

A machine was rumbling at his side. Thin green lines were in the screen. Some numbers were shown too. Serum dripped with it's inevitable calm into the intravenous syringe attached to your arm.

Sky blue curtains surrounded you, leaving an isolated square where you rested.

'A hospital...'

You recalled everything. The fights, the train, Akaza... and your loss against him.

"Umai. UMAI!" A loud voice came from the other side of the curtains.

"Huh?"

"R-Rengoku-san, if you're too loud, (YN-San) is going to wake up."

A soft and gentle voice was there too. You knew almost immediately who was it. He received a beating too during this hell known as school trip, but it was worth every single scratch, bruise and blood he spat.