Demon Lord's Reincarnation

In the underground waterway of the city, the Shadow Clan and a group of people were walking through the stream of water. Albert was at the front walking alongside one of the unnamed members of the Shadow Clan. He was rather surprised that these people know about these ancient waterways. This wasn't the waterway system that the current city was using, this was one that felt older was from a different era. Even though he had lived in this city since he was a boy, Albert had no idea that these waterways even existed. He was very impressed with how prepared the Shadow Clan was, that they even know about this place. 

As the continued walking the shaking from above was getting more intense. Even though they were underground they could still feel the vibrations of the fight on the surface. This frightened some of the people.

"Aren't you guys worried about the kid?" Albert could no longer stop himself from asking. 

"The kid? Oh, you mean the commander. Why should we be worried about the commander?" 

Albert already had some suspicions but still hearing it made him feel weird. 'So the kid really was the leader of the group.' 

"No matter how strong he is, there are too many enemies. Also, it leaves a bad taste in my mouth to leave a child at the rear." The person Albert was talking to looked at him confused and then he chuckled. 

"Oh right, the commander is supposed to be a child. I always seem to forget that, since he's always so mature and scary." Albert was surprised by the reaction made by one of Arthur's comrades. 

"Don't worry about the commander he can handle things by himself. Also if we were up there we will only get in the way, plus if any of us were up there we'll all be killed. Once the commander uses that technique everything moving will be killed no exceptions. So the best thing to do is to leave this place as fast as possible." Unable to understand what was said, Albert still looked worried. 

"Still..." 

"Our mission is to kill all of those that don't surrender. As for those that surrender they will be protected no matter what the cost. We will not fail our master. The commander knows this so he will never lose. The motto of the Shadow Clan that our master created, is ABSOLUTE VICTORY. Nothing less is to be expected, and this being our first mission as a true unit, failure was never an option. Also, do not be fooled because he is a child, age doesn't matter when it comes to strength. If he cannot win the commander is capable enough to escape."

Even though he said all that he knew that the commander would never retreat. Even when facing Ren himself, Arthur never backed down. Arthur was neither scared of death nor was he scared of facing overwhelming odds. The only thing that scared Arthur was that he would once again be powerless to do anything.

When Albert heard the Shadow Clan member's response he was once again surprised. The way he spoke, the conviction in his voice showed how much he trusted the child called Arthur. Not only was Arthur extremely talented as a warrior, but it would seem that he was also talented as a leader. 

'Now I'm even more interested in the one who trained him. Just how powerful is this master of theirs, that he could train such elite warriors?'

...

While the Shadow Clan members and those they were protecting were almost out of the waterways, on the surface the once beautiful city turned into a land of death and destruction.

Arthur was an unstoppable force of nature as he tore through the droves of people. No matter what kind of defense they put up it was nothing more than paper in front of Arthur. Those that wished to surrender could no longer do so as Arthur couldn't even hear their voices as he killed them. They were many begging for mercy, but Arthur in his berserk state did not stop as he continued to kill all. 

A lot of the nobles who came to the Duke's mansion regretted their decision to come today, as they watched their armies being wiped out by a single person. They wanted to retreat with some of their men, but they couldn't get too far before they were crushed to death. 

Reginald, who was sitting there looking at the horrible sight before him in horror. He couldn't believe what he was seeing. Today was supposed to be his most glorious day, as he stood above all the other nobles of the Serbek Kingdom. Today he was supposed to lead the armies of the noble families towards the Capital to destroy the traitors and execute the fake king. He was supposed to take the throne and live his life and become a legend forever remembered. Yet now all of his plans and his dreams were being crushed by a single boy. It wasn't even the fake king that came, he simply sent his young disciple to deal with him. It was as if Ren was telling him that he was unworthy of his attention, as he didn't even send the S rank adventurer Lara or the rumored Hero Valdel. 

'No, no, no, no, no! This must be a nightmare. Yes, it's all just a nightmare, a very bad nightmare. Once I wake up all the glory and worship will be mine. I will become a legend that will last forever. This is just a nightmare, yes nothing but a nightmare.' Reginald's mind was slowly falling as he continued to deny the reality of his situation. 

...

The battalion stationed at the rear that was composed of young noble heirs who came here to gain experience were shivering in fear as they watched the battle from a distance. It was a good thing that they had fled before they were seen by the monster. 

Surely at this distance, the monster wouldn't be able to spot them. At first, they wanted to leave immediately but now that they felt safe from this distance they were compelled to watch. They didn't know why but they could not look away from the massacre that was happening in the city. The savagery of Arthur's fighting style was both fearful and inspiring. There was a wild beauty to it. 

"We should leave now, else he spots us." One of the heirs spoke a little scared by the whole event. 

"Yes, we should probably leave now. Now that our family heads are dead we should head back to our lands, and once we settle down in our new positions we should all go and meet the current king and apologize." 

"What the f*ck are you cowards saying! Bow to the false king who came from our enemy nation?! I can never do that?! Also, are we really fleeing and leaving our family heads to die?!" 

Everyone looked at the screaming boy as if he was an idiot. 

"If you want to save your family head then go ahead be our guests. Unlike you, we don't want to die just yet."

"Yeah, if we go then all of us will just be annihilated." 

"If you don't want to bow to the new king, then sure, we won't care about that. But if you want to bring us back into that city were that disaster is continuing massacring the soldiers, you're on your own on that, don't lure us in." 

"If you're so brave, then go and save your family head." 

"..." The boy wasn't expecting that all of them would be that angry at what he said. Also, not a single person took his side. He gritted his teeth as he looked at every one of those that mocked him. 

'I will remember this, I will get my revenge on you all, that boy that killed my father, and the false king. I will take my revenge no matter what.' The boy started planning on what he would do to take his revenge and as he was thinking, one of the people watching the massacre that was happening in the city suddenly shouted. 

"Everyone RUN!" The boy who shouted tried to move as fast as he could to escape the thing that was coming. When the others heard his shout they too didn't think too much and immediately tried to flee. Yet before they could even move two steps a beam of mana had scorched their position.

The family heirs all screamed in pain as they were being burnt alive by an immense amount of mana. They couldn't breathe and the pain they were feeling was intense. They now regretted that they didn't leave when they had a chance. The despair they felt as they died was so intense it felt like their very souls were crying. 

The boy who promised to get revenge was trying his hardest to stay alive. He was using his mana to try and regenerate, but it was to no avail. His mana was too little to be able to resist such a powerful strike. 

'Why?! I haven't gotten my revenge yet. I haven't been able to do anything yet! I don't want to die, I don't want to die! I don't want to die! I don't care if it's a God or a devil, anyone, I will give anything just allow me to survive so that I can take my revenge!'

Yet no matter how he pleaded no one listened to his pleas, neither the Gods from high above nor the devils from down below. The boy's consciousness was slowly fading as the pain disappeared and all he felt was deep regret.