Backstory - 1

A/N: It'll be switched to 1st person now.

<Protagonist's POV>

Realizing what I, or rather, Mizuki Kioshi had just done, I couldn't help but grimace.

Just an hour or so ago, Kioshi and his twin sister had done the deed, losing their virginities to each other, and at the age of 13 no less!

I was appalled, but, what could I do? The deed was already done, and there was nothing I could do about it.

Looking down at my hands, I realized that I had been unconsciously stroking my sister's head.

Looking at her, I had to marvel at how we looked so much alike.

After all, the only difference between our two appearances was that she had long hair whilst I had short hair, other than that, we looked like we were identical twins.

We were even both still flat, as I had yet to get pecs, and, well, she had yet to acquire "womanly pecs".

Well, there was also the fact that the kizashi, which were the only remembrance of our parents, were in different places in our hair.

I just stuck my kizashi in a random place in my hair, where it dangled loosely, while, on the other hand, Yasu used her kizashi to keep her hair from falling into her eyes.

(A/N: Kizashi is the name for traditional Japanese hairpins.)

Looking at her, I couldn't help but think about "my" childhood.

At the age of 7, our parents had died in an unknown accident. All we knew was that we had been out playing for a while, but then, we had come home to the sight of our parents murdered, their ripped off limbs scattering their room, in a work of eerily beautiful art.

Yasu had just stood there, frozen in horror, squeezing my hand tighter and tighter until dark purple bruises started appearing, but I didn't mind, as I was mentally shocked too.

Recovering first, I immediately ran to the neighbor's house before telling them what had happened.

All the adults of the village had come together to try and figure out what had happened, but, they were never able to find the culprit.

Taking pity on us, a kind family had let us take shelter in their house for a little while, as the rest of the adults in the village had cleaned our house and had made graves with the remainder of our parents' bodies.

Then, we had moved back in, but not before barricading the door to our parent's room.

After the incident, I had become the handyman of the village, taking odd jobs for the other villagers in return for food and other necessities like second hand clothes for when Yasu and I grew out of our old ones.

Yasu had also taken to doing odd jobs like washing dishes and doing the laundry for other houses, and just like this, us pair of siblings were able to barely scrape by for the past 6 years.

And, well, there was another thing about us.

Due to the emotional trauma that we had sustained during the incident, we had both grown unable to speak, and even though "I" was now transmigrated into this body, I still couldn't, as our memories had merged, and so, our individual traumas and personalities had also merged.

But, this wasn't smooth the whole way.

Like, right now, I was constantly fighting a war in my brain, with each side trying to justify themselves.

Of course, what they were trying to justify was whether I should be doing this with my sister or not.

The personality from Earth was completely disgusted by my actions, whilst the personality from this world was too much in love with my sister to let go.

And, honestly, the more the two sides fought, the more that the personality from Earth understood the situation.

After all, Yasu and I only had each other for the majority of our life.

We had mourned our parents together, it was I that had picked her up when she was in the darkness after our parent's death, and it was her that had picked me up when I was in the darkness after another event that had left me traumatized for a second time.

We had bonded with each other to the point where we could understand each other without any of the gestures that we usually used to communicate with other people, our eyes were all we needed.

And, we had fallen deeply for each other.

But we actually hadn't been lovers for a long time.

Today had just been a normal day, with us waking up in the same bed and bathing together.

Of course, this was as siblings, not as lovers.

But, this "act" as siblings all came to an end in the evening as we both confessed with our eyes to each other.

You see, we had been harboring our own emotions for each other for a long time, but we had never expressed them, as we were both afraid of breaking the taboo.

Today was different though.

Both of us, as if we were on the same brain cell, had confessed to each other without warning.

It was as if we had both finally mustered up enough courage and told each other how we felt.

After confessing to each other, and realizing that we were the same, we had taken each other to bed, a night of heat and sweat ensued, and the rest was history.

Back to the present, I was currently trying not to disturb my naked sister who was lying on top of my body right now.

Now that I had accepted the situation, and my love for my sister had won out, there was still one thing though.

I couldn't help wondering if we had gone too fast with each other.

I mean, the first time we kissed and the first time we had sex was on the exact same day.

But, my thoughts were suddenly interrupted as the noise of wood breaking sounded from the front of our houses.

Pushing Yasu off of me, I quickly dressed and ran out of our room to see what the commotion was about.

Standing in the space where our front door had been stood a man wearing an embroidered black and white suit with black curly hair and a white hat with a black sash running around it.

'So this is the world I got transmigrated into, and this must be the event for me to gain my power, a little bit earlier than I had expected to be honest.'

After all, standing in front of my was none other than the progenitor of all demons, the personification of death itself in this world.

Figuring out the person's identity, I finally worked out which world I had been transmigrated into, the world of Demon Slayer.

Steadying myself, preparing to gamble with my life on the line, I took a deep breath, taking out a piece of parchment and writing,

"Muzan Kibutsuji, what brings you here?"