Reincarnated as an Energy with a System

The Demon King used the [Demon King's Roar] spell making the young man flinch in fear. He used a cleansing spell on himself to remove the fear and got ready for the attack.

The Demon King shot forward at an incredible speed. With his wings, he glided through the air as he arrived in front of the young man. He swung his sharp claw at the young man, nearly ripping his skin out.

The young man jumped back in fear and took out a small thorn from his interdimensional storage. It was actually a quill that came from a demonic echidna he had killed not long ago.

The B-ranked monster wasn't the most strong, but the poison in its quills was some of the most toxic things the young man had ever seen.

So, he planned on using it on the Demon King today.

As the demon king was flying towards him again, the young man threw the quill at him. The quill struck his chest and surprisingly pierced him, immediately poisoning him with the demonic echidna's poison.

However, that wasn't all. [Poison Touch], [Caustic Burn], [Decaying Touch] and other few similar skills were also activated when his quill landed on the demon king.

"Aaagh!" the Demon King shouted in pain and fell to the floor. He fidgeted on the floor like a fish out of the water while constantly shouting in pain.

The young man breathed heavily as he watched the Demon King cry out in pain. Had he done it? Was this it?

No, this was bad. If the demon king died… who was going to command his army to return? They were already on their way to his world. If they weren't stopped, such strong demons would raze each and every city to the ground with rather ease.

However, the Demon King was a figure that he couldn't just save. His death would mean that so many more would get to live.

Not even just his world, but all the other worlds that this person was attacking.

"No, I must kill him," the young man thought.

"AAAHHH!" the Demon King continued crying on the floor in pain, so the young man slowly moved forward with his dagger. Just one single attack was all he was going to need.

A single stab to the head and the Demon King would die. As for his four generals, the young man decided to spread the message of his death to force them to return.

"You will have to die now," the young man said as he arrived in front on the fallen Demon King and stabbed downward.

Suddenly, the Demon King's hands moved at lightning speed and grabbed the young man's wrist before he could deliver the blow.

"AAAAAHAHAHAHAHA," the Demon King's cries of pain turned to laughter all of a sudden. "Haha, did you really think a simple poison attack was enough to kill me? The Demon King? Do you think you are the only one with so many skills? Boy, you have no idea what it means for one to be a Demon King, do you?"

The young man looked at the Demon King with a shocked look in his eyes. He was mistaken and baited to attack the demon who wasn't even in pain. Now that he looked at it, the poison quill hadn't even done anything at all.

"No!" the young man said in horror and brought down his other dagger to stab the Demon King's head. But before he could do it, something flashed, and in the next second, an intense pain spread through the young man's body.

"Aargh!" it was the young man's turn to cry out in agony this time.

The Demon King stood back up while still holding the young man's other wrist and looked at the hand he had just cut off.

"So weak," he said while shaking his head. "What were you thinking? How strong even are you?"

He quickly analyzed the young man and sighed. "So many skills, but without any practice, those are all useless. As an S-ranked fighter with little to no experience, did you think you could kill me, the Demon King?" he asked.

The young man was losing focus due to the lack of blood but his passive healing skill was trying to help regrow his arm as well as it could.

However, the loss of mana before he had come here was the biggest problem for his healing at the moment. Even then, the Demon King noticed it and couldn't help but frown.

He slammed the young man onto the ground, creating cracks all over his floor. "It seems I underestimated you just a tad bit," the Demon King said. "Had I left you alone, you would've healed again and come back to kill me, wouldn't you? I'm not going to make that mistake."

"There are many questions I want to ask you about how you came here and why you were able to hide from my scouts, but none of that matter right now. All that matters is that you are here, and you are going to die," the Demon King said.

The young man grunted and tried to say something, but the Demon King gave no thought. "Die!"

He lifted his feet and slammed them down on the young man as hard as he could. The ground cracked beneath his foot and a small crater appeared in the throne room. However, the Demon King did not feel a body beneath him, just air.

"What's happening?" he asked with a confused look on his face. "What are you doing?"

He lifted his feet and looked at the young man, but the young man was just as puzzled as he was. He had expected to die just now, but somehow he had been saved.

"Phew!" A voice spoke from the side. "I wasn't aware I would have to save someone in here. I would've come earlier if I knew that."

To the shock of both the young man and the Demon King, a third party had arrived.