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Angel Investor, Demon King

Summary:

“I want you to kill me. For ten billion dollars.”

Yoo Joonghyuk, a washed-up hunter running a dying demon pest control business, gets an offer he can’t refuse—from the 73rd Demon King himself.

Now all he has to do is figure out how to kill the unkillable.

Chapter 1: 10 Billion

Chapter Text

 

Sometimes, Yoo Joonghyuk wondered if this was all his life had amounted to.

A shriek split the air behind him.

He turned and beheaded the demon in a single swing.

Another burst through the rooftop shingles. A third crawled out of the storm drain, gnashing teeth and stunted limbs twitching. The pests were getting bolder again. No pattern, no reason. Just mindless puppets wreaking havoc.

Yoo Joonghyuk cut them down one after the other.

When the last carcass hit the ground, he wiped the edge of his blade, then raised the flare gun and fired into the sky.

A streak of green exploded overhead.

Extermination complete.

The surrounding blockades dissolved. Pedestrians poured back into the street like water filling a trench. Some groaned about traffic. Others checked their phones or cursed at their smart glasses. A businessman stepped over a demon corpse like it was gum on the sidewalk.

No one spared him a glance. Walking past him as if he didn't exist.

Just another extermination. Just another cleanup job for the lowest rung of society. Pest control with a license to kill.

Demon horde had shattered with the fall of the 72nd Demon King. What remained were scraps, brainless, starved things crawling through gutters.

Only one true demon remained.

And no one knew where he was or what he wanted.

And nobody cared. So now, everyone just treated demon emergencies as a new normality. Desensitised to it as if they didn’t threaten the world just several years ago.

On his way back to base, Yoo Joonghyuk passed a small plaza that hadn’t existed ten years ago. Neon signs flickered over fresh pavement. Families gathered outside cafés and biotech kiosks.

A digital billboard flickered above the square.

A woman’s voice rang out, smooth and saccharine:

"Brought to you by the Fourth Wall Group. When fate won’t change itself… break it!"

The screen shimmered with light. 

"Fourth Wall. Because this world is yours to rewrite."

Yoo Joonghyuk squinted at the screen.

He didn’t know what annoyed him more. The slogan, or the smugly cryptic tone.

Then, his gaze turned when a little girl ran past him, laughing.

Black hair. Pigtails. Skinny arms stretched out like wings.

A man and woman, presumably her parents, caught her a second later and swung her into the air like a pendulum.

Laughter echoed.

His hand clenched involuntarily. He couldn’t look away.

Mia.

A beat passed. Then two.

He turned his head and walked on, jaw tight.

Peace had come at a price.

A price he wasn't willing to pay, until fate decided to snatch it away from his hands anyway.

 


 

Skybreaker Corp was as worn down as he was. What used to be a fire station now held the bones of a struggling extermination company. The paint peeled. The wards buzzed. The lights flickered in time with his bank account.

"Captain." Shin Yoosung approached him.

He looked.

"About the meeting today," she handed him her tablet. "The founder himself will be coming."

He raised an eyebrow.

“Fourth Wall,” she said. “Kim Dokja. He’s on his way.”

He paused mid-step.

Fourth Wall wasn’t just another investment firm. It was the firm. They funded everything from weapons to biotech to privatized hunter agencies. Their logo was stamped on every government-endorsed hunter equipment in the market.

“What the hell does someone like that want with us?” he muttered.

Shin Yoosung shook her head. “He didn’t say. Just that he wants to hear the pitch in person.”

“We didn’t even pass the second screening.”

“He asked for you. By name.”

Yoo Joonghyuk’s eyes narrowed.

“…Fine. I’ll handle it.”

As he was about to step away, another headache came.

“Master!”

Kim Namwoon skidded into the hallway, waving a device with exposed wires.

He had skipped all the approval process. Something would break in the next few days, for sure.

But he listened anyway.

“Hear me out. Picture it. A super demon detector prototype! It automatically pings the nearest hunter base when demons are within ten meters. And! It rings like a flood siren!”

Yoo Joonghyuk blinked at the device. “So... the same as the government system?”

Kim Namwoon grinned. “But this one’s ours. This genius wrote the code in less than two hours.”

“That explains the last outage.”

“It’s agile!” Kim Namwoon said proudly. “You said to streamline ops, right?”

“I also said not to fry our internal network.”

Yoo Joonghyuk exhaled slowly, rubbing his forehead. “Rejected.”

Kim Namwoon groaned and skulked away, already muttering about v2.1.

He was halfway to his office when Lee Hyunsung jogged toward him.

“Captain! About the budget reports—”

“Later.”

Behind him, Jung Heewon was already eyeing him with a stack of papers.

“I need these signed—!”

“Later.”

And then Yoo Joonghyuk, once a war hero, now a glorified team lead of a mid-tier hunter company, did the most dignified thing possible.

He vaulted out the window.

He landed on the street and walked off without looking back.

The base would hold itself together for five more minutes.

Probably.

He made it one block before a sleek, blood-red designer car turned the corner and stopped in front of the building.

Tck…what timing.

That must be him.

And sure enough, by the time Yoo Joonghyuk circled around to re-enter from the alley and leap back through the second storey window again, a knock came at the door.

Shin Yoosung poked her head in. “He's here.”

Yoo Joonghyuk sighed.

So much for buying time.

The man who entered looked like he’d walked out of a luxury brand campaign. Slender build, expensive suit, that irritatingly pleasant smile rich people wore like perfume.

“Thank you,” he said warmly. “I’ll take it from here.”

She gave a short nod and shut the door.

And immediately, Yoo Joonghyuk felt it.

His instincts screamed.

No sigils. No mana spikes. No demonic aura.

But something wrong had just entered the room.

Yoo Joonghyuk’s grip tightened on the table, though he made no move.

“Welcome to Skybreaker Corp,” he said flatly. “Let’s keep this brief.”

“Of course,” Kim Dokja said, eyes warm, tone casual. “Please. Go ahead.”

Yoo Joonghyuk launched into the pitch. He laid out their strategy: expansion into high-tier extermination zones, development of autonomous scan towers, potential partnerships with low-cost gear suppliers. All the usual stuff.

Things that he could recite in his sleep.

Kim Dokja didn’t look at the slides. Not once.

His eyes tracked only Yoo Joonghyuk. Unblinking.

He didn’t even glance at the figures. His eyes never moved.

It was unnerving. Like being dissected by something that had worn human skin for too long.

But Yoo Joonghyuk pressed on. He finished the pitch exactly at the eight-minute mark.

And still, the man’s eyes were still zeroed in on him.

“Do you have any questions?” he asked.

Kim Dokja smiled.

“Ten billion dollars. For a hundred percent ownership.”

Yoo Joonghyuk blinked.

“…What?”

Yoo Joonghyuk’s brain short circuited.

“...Did you mean won?”

“U.S. Dollars.” Kim Dokja accentuated every word.

Yoo Joonghyuk’s face darkened.

“That’s a ridiculous amount. We’re not worth a tenth of that.”

Kim Dokja leaned back in his seat, still smiling.

“I know.”

His tone wasn’t mocking. It was factual. Making it all the more insulting.

“You think this is funny?” Yoo Joonghyuk asked.

“Not especially.”

“Then why?”

Kim Dokja’s eyes gleamed.

“Because I’m investing in you.”

Yoo Joonghyuk stood, tension rolling off him. “I don’t need a savior. If you think I’ll sell this company out of desperation—”

“It is not the company I want,” Kim Dokja cut in. “I want to own you.”

In a blink of a moment, his shadow warped.

The room darkened.

His eyes gleamed red.

Shadowed wings stretched long, jagged, impossibly wide. Twisting until they covered the floor and walls. A pair of horns split through the side of his silhouette, piercing the ceiling.

Yoo Joonghyuk didn’t think. 

Disgust shattered his restraint in an instant.

He moved.

In a flash, his sword was drawn and buried in Kim Dokja’s chest.

Steel sank cleanly through the bones, into flesh.

Kim Dokja winced, looking down at the blade.

“…Ow,” he said, almost too cheerfully for a man being stabbed. “You really don’t waste time, do you?”

His eyes met Yoo Joonghyuk’s, unflinching.

“That was a good start.”

The wound hissed and began to close.

Yoo Joonghyuk’s eyes widened.

“But I’m not so easy to kill.”

His sword cracked.

“That’s why I need you.”

Then it snapped in half.

Yoo Joonghyuk stared at the broken hilt in his hand.

The demon’s wound was already gone. Only the torn suit remained

For the first time, Yoo Joonghyuk didn’t know how to kill the enemy in front of him.

And he realised. Sitting right there, in a suit, and a polished smile was none other than…

The 73rd Demon King.

“I want you to kill me,” Kim Dokja said, voice unnervingly pleasant. “For ten billion dollars.” 

He smiled.

“No installments.”