Thus darkness is born

Monster! 

No one thought that Isao was a human. 

All the demons who saw Isao's power thought that this young man was a monster in human form! 

All the demons were destroyed without mercy, and there was no room for hope. 

As they had met him, their only destination was to die. 

"Ah, I don't want to die! I don't want to die! I want to stay alive!" 

The cowardly demon, Hantengu, quickly thought of running away as far as possible. 

Meanwhile, Gyokko, the demon that lived on the vase, laughed, but his laugh wasn't as free as before, and his eyes were filled with intense fear. 

"Hyo~! Hyo~! Hyo..." 

Yet, as they had already entered Isao's vision, it was impossible to escape. 

The moment they were about to move, their bodies were dismembered into several pieces by Isao before he devoured their DNAs. 

There was also a demon that could run away so fast, but Isao cut it down before it was about to move. 

There were many other demons with a variety of abilities, from controlling a ball, sound, red arrow, dream, string, and many others. 

All of them were killed without any chance to fight back; they were like a group of sheep that were helpless against the hungry wolf. 

"RUN AWAY!" 

"NOOO, DON'T KILL ME!" 

"FORGIVE ME! FORGIVE ME! PLEASE, I BEG YOU—" 

Yet, no matter what they said, they were all killed by Isao. 

At that moment, Isao was more like a demon than them. 

However, Isao didn't feel guilty since he knew that all of them had tortured a human, and all of them enjoyed tormenting those innocents, giving them terror, and slowly killing them. When those innocents begged for them to give mercy, did this group of demons ever think to let go of those innocents? 

No way. 

For the demons, a human was nothing but food, and it was impossible for them to give mercy toward their food. 

With all of that, it would be silly of Isao to let them go. 

Oh, he also met a demon who should be the student of Jigoro, the former Thunder Hashira, who had transformed into a demon. 

"Forgive me! Please let me go! I was forced to become a demon! I-I am still a Demon Slayer! Please let me go, okay? Please let—" 

Isao killed him and gained his DNA, which gave him the ability to manipulate electricity.

On the other hand, Muzan, who had regained his body, quickly tried to chase after Isao to stop him from killing Biwa Demon. Naturally, Tamayo tried to stop him, but with her strength, all she could do was buy time before she died. Frankly, she wanted to use the napalm bomb created by Isao, but Isao didn't let her keep it, which annoyed her since she knew that with her strength, she would be defeated soon. 

"YOU HAVE MADE ME ANGRY, TAMAYO!" 

Muzan was enraged and was about to give a last blow to Tamayo, but suddenly, the architecture of the Infinity City changed into a different shape, pulling Tamayo away and trapping him in a place. 

"No! This is...?!" 

At the same time, Muzan receives memories of all the demons who were killed by Isao. 

Not only Kokushibo, Biwa Demon, and many others. 

All of their memories and how they were killed entered his head almost at the same time due to Isao's speed in killing those demons. 

"No! No! No!" 

As Muzan fell into despair, Tamayo was confused, wondering how the sliding door could suddenly pull her away, but she knew that it was almost time before everything had ended. 

As expected, Isao soon returned, walking like a butterfly floating in the air, which made it impossible to guess how he was going to move next. 

Yet Muzan, who didn't see any hope in defeating Isao, begged. "Don't kill me! I will do anything! I can give you an eternal life! Woman! Wealth! Anything! I can give you anything! So let me go! Let's work together! As long as we're together, then this world is as good as ours! So, don't kill—

Before Muzan finished his words, his head was beheaded. 

Still, this wasn't the end of the day after Isao raised his poleaxe and smashed Muzan into pieces as he devoured Muzan. Unlike before, when he did it discreetly and only absorbed Muzan's body parts, which he had cut. This time, he absorbed Muzan's everything. 

However, Muzan, who was still alive, especially his soul, realized everything. Before him was a bottomless abyss that would swallow him and everything. After this, he would disappear from this world and become a nutrient for Isao. 

Yet, this also made Muzan laugh. 

"Hahaha...! I see! I see! This is why you wish to devour me! You are a much more vile creature than me! You are going to devour all of the demons for your own use and control humanity, right? I can see everything! You evildoer! Villain! But I, Muzan Kibutsuji, have lost to you, so you have to bring the darkness to humanity in my place! 

"Bring the despair, pain, and tragedy into this world for me, Iinuma Isao!" 

As his soul was devoured by Isao, becoming part of Isao's power, Isao was speechless at Muzan's last words. 

Bring despair, pain, and tragedy?

What he would bring was happiness, hope, and warmth! 

How could he become a devil that would ruin this world? 

As for Muzan's strong soul, which wanted to wreak havoc inside him, Isao thought that Muzan thought of himself too much since if it was the power of his soul, he wouldn't lose to anyone, especially when he was reincarnated. 

His soul and spirit were his strongest points! 

Yet—

"...is that true?" 

Tamayo looked at Muzan's body parts, which had been absorbed into Isao's body. She knew that Isao had devoured Muzan and that Isao wasn't a human but something entirely different being. 

Then, was he an existence that would bring this world into ruin? 

Isao looked at Tamayo for a moment and nodded. "He is right, so you should kill me." 

However, hearing his answer, Tamayo snorted and leaped to him, hugging him tightly. 

"...don't do this. It is inappropriate." 

There were many corpses of demons in this place, and he had just finished his battle, but this mature woman touched his penis so boldly, caressing it, and grabbed it with a force that made him feel comfortable. 

Watching him, who wanted to run away, Tamayo didn't let him go and hugged him even leaper while caressing his hardened cock that gave her happiness. 

"Even if you are not a human, it doesn't matter. I am also a demon, after all. We fit together. Even if you are evil, I am not good either since I have killed many, so don't think to escape, especially when you have made me pregnant." 

"...re-really?" Isao looked at Tamayo, who looked at him with an affectionate gaze, feeling helpless as he didn't wear a condom that night. 

"Um." Tamayo nodded shyly, letting him hold her flat belly. "If it's a human, they might not feel it this early, but I can tell that there is a life in my womb." She was a demon that could control parts of her body, so naturally, she felt the life in her womb. She wasn't sure how their child would be as it was a child between a non-human, but even so, she would treasure this child. 

"So, don't even think about dying. Don't leave us." 

"...." 

Isao fell in silence, feeling her trembling hands cling to him tightly. Even though he could pull her away, he hugged her in his arms as he changed the location so he could see the beautiful lakes with many piers around. 

The blue glow of the lake appeared beautiful, giving a gentle and warm light. 

Only all of the light disappeared as soon as darkness was born, leaving the world in a completely different direction, which one never guessed.

However, as the world began with darkness, everything should be okay.