The Fallen Hero Reincarnates as the Demon King's Son

'Is this what happens after death?' A young, scarred soul thought.

The owner of that soul was Caliste. He was renowned as humanity's greatest hero, the savior of this world. However, it all came crumbling down during his final fight against the demon king, where even his closest friends decided to betray him.

They betrayed him and did not once look back.

That's why, as Caliste felt his soul being pulled into this eternal darkness, a small rage was still bubbling within him.

His entire life's goal had been worthless.

'Those bastards… if only I could get my hands on them. I would make sure that they suffer.'

[Your anger has been recognized by the heavens.]

A loud, mechanical voice suddenly entered his mind.

'What is this?'

He had never heard anything like this. For the better part of his life, the heavens had been dead quiet, letting humans face off against the demons on their own.

[They have a proposition for you.]

[You will reincarnate as the Demon King's newborn, making it easy for you to kill him when he lowers his guard once you grow powerful enough.]

Caliste frowned as he heard those words.

'What are those arrogant angels even thinking?' He shook his head. 'Making ME a demon? They have got to have lost their minds.'

[This is for the greater good of this world, Caliste Henry. If you do not accept this request of ours, then the world will succumb to the demons.]

Caliste didn't think anything. He knew those angels could hear everything he thought.

However, there was one thing those demons had not anticipated.

The hero had fallen.

What if he no longer wanted to be a hero?

What if he finally wanted to live for himself?

Heh. Then a disaster would happen.

'So, let me get this straight. I will reincarnate as the Demon King's son?'

[Yes, that is what will happen. You will also receive help from a helper; the form is not yet determined, but it will be a tool that will accelerate your growth by a large margin, making you a real threat to the Demon King extremely fast. Now, what do you say? Do you accept our proposition?]

Caliste thought about it.

Death or a second chance at life. And let's be honest, he didn't need a lot of thinking. His choice was easily made.

'I accept.'

[The Last Hope Project has been launched.]

[Initializing…]

[0%…25%…35%…]

…

[100%]

[Reincarnation in progress…]

[Found adequate soul.]

[Teleportation launched.]

Then, as those words entered his mind, Caliste's soul began being pulled away in a completely different direction.

The darkness no longer surrounded him as a bright light blinded him.

He flew across the sky at a speed that had never been achieved before. He went past forests, cities, and battlefields until he finally reached his new home.

A gigantic castle on top of a floating hill.

The very place where he had died, with the slight difference that it looked extremely peaceful now. There was no longer any damage to the castle.

-Swoosh!

His soul then accelerated as it went through a window right into the body of a baby, the Demon King's baby.

[You have entered your host's body.]

"Hm… my precious baby!" A beautiful demoness with long red hair and two pointy horns said as she held her baby, or rather, Caliste, tightly in her arms.

"So soft! Argh… I can't even breathe! Let me go!" Caliste tried to say, but the only thing that came out of his mouth were squeaky noises.

He was being squeezed against this demoness' ample chest.

While he complained, there was also a little smile on his face. While he had been trying to save the world, Caliste had never really entertained the many women around him.

But that was about to change in this life.

He would no longer live for others.

He would finally be living for himself.

'Thanks for the second chance at life, idiots!' Caliste thought with a big smile.

"Um… what should we name you?" The demoness said as she pulled Caliste away from her chest and raised him a little above her head, admiring him.

"Yike?" She shook her head. "Hm… maybe Caliste?"

She thought for a few more seconds and smiled again. "Yes, that's perfect! Your name will be Caliste!"

The woman hugged him again, squeezing him against her huge breasts once more.

But then the door was swung wide open, revealing another beautiful woman. This one was definitely younger; she looked to be around 18 years old. However, guessing the age of a demon had always been extremely tricky, since they lived for thousands and thousands of years.

"Mom! Are you trying to kill him?!" She screamed.

'Hm… is that my sister?' Caliste thought with a slight frown.

He had never seen her in any of the battles he had participated in.

After all, he wouldn't have forgotten about such a beauty.

She had long purple hair, two cute horns poking out from her forehead, a perfect face, and more importantly, her body was literally perfect. Her clothes fit her perfectly, showing her curves and slim body.

'Are all demons supposed to look this good?' Caliste thought, as he had never really noticed until now.

Until now, he had always thought about killing them. But now that he had a closer neutral look, he could say with certainty that his sister and his mother were extremely rare beauties, beings that any normal man would chase around the world for a chance to marry them.

"Tsk, Aleia, why are you cursing me in front of your little brother?"

Aleia, Caliste's sister, slowly approached her mother and Caliste. Her loving gaze landed on her brother, who was peacefully looking back into her eyes.

"Mother, can I hold him?"

Caliste, who heard that, brought his arms forward, practically asking for his sister to hold him in her arms.

"Oh… he's so cute. He already loves his big sister! Did you see?"

But then, just as Aleia was about to grab Caliste, Ava, Caliste's mother, turned around sharply.

"You know the rules. We have to get him examined and make sure that everything is fine with him. Call a maid; I want to get this done as soon as possible."

***

A few minutes later, Caliste was lying inside a baby bed with the eyes of three people carefully looking at him.

"Is there something wrong? What do you think?" Ava asked.

The maid frowned slightly. "Hm… I'm not sure. For some reason, Caliste's natural circuit seems to be blocked at many different places in his body. Normally, this could be fixed with an elixir, but his situation seems extremely severe. It's as if his mana circuit is corrupted."

Ava's eyes widened, and so did Caliste's.

'Corrupted?! What the hell is this shitty body?' Caliste looked up at the ceiling of his room. 'You scamming angels! Fix this right away!'

However, this time, there was no response.