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When our world faced problems it could never overcome on its own, we summoned beings from other worlds to lend us their strength. Otherwise, tens of thousands, even millions, might die. There was no choice. We were taught, and came to believe, that such summoned beings were saviors, heroes to be revered. And it was true, once, my world was saved by a hero called from another world. That hero defeated the enemy of our world, and their descendants guided us into an age of peace.

But when the summoning turned on me, I learned I could not be so noble.

I was summoned as a hero, only to be remade into the Demon King, Zygos, and set down in this land. Back in my own world, I had just fulfilled my duty as the descendant of a hero; I had slain the lord of the monsters who threatened our people. After great sacrifice, the war against the monsters had ended. A fragile peace had finally come. We would rebuild our ruined cities. We would lay flowers for the fallen. We would look forward, creating a new era.

I’d slain the enemy’s leader, yet there was still much left for me to do. So many things I wanted to accomplish.

And yet, I was kidnapped into another world. At the same time, I was remade into Zygos and forced to understand the reality here. I had been brought to a world on the brink of collapse.

And the world’s collapse was tied to my own death. My life itself has become the world’s lifespan. No matter what I did now, it was already too late. There was almost no meaning to my being summoned. In truth, I had been summoned for no other purpose than to die. It was like being handed a death sentence.

It was fortunate, at least, that I was chosen as Zygos. Otherwise, I might never have even learned the truth. I might have obeyed the country that had summoned me blindly, knowing nothing, and awaited the end. It was also fortunate that Zygos’ mission, in this era, was to slaughter the people of this world.

That way, my vengeance, my rage, was something this world itself acknowledged. I could carry it out with my head held high. That I could even say such a thing meant I had already changed. The person I had been before being summoned, before becoming Zygos, no longer existed. And I was lucky not to harbor hatred toward beings from other worlds. Had I turned my resentment on the comrades who fought beside me in my original world for no reason, then I would truly have ceased to be myself.

The fools who summoned me here, who shortened this world’s lifespan, I had already killed. But there were still countless hateful beings crawling nearby. And since that aligned with Zygos’ mission, I’d begin by reducing this kingdom to nothing. Let them taste terror to their last breath, and vanish knowing exactly what it meant to have summoned me.

Having decided, I swung down the greatsword I had possessed since the moment I came to this world. The wall split. The ceiling split. With a thunderous crash, the building, the castle, no doubt, began to collapse. Even if they did not understand exactly what had happened, the people would at least know something terrible was unfolding within their kingdom. My body felt no different. I had not been granted superhuman strength.

All I had been given was this greatsword and a body that nothing in this world could touch. And that was enough. If I had been given unnatural speed or strength, I would only have wasted it.

“Your Majesty! What? … Is this your doing?”

Perhaps because of the spectacle, knights came rushing in. They had come to check on the king, but seeing his corpse drenched in blood, they raised their weapons against me. I thought they had no time for such foolishness until I noticed the wings sprouting from their backs.

(Ah. They can fly. In that case, if they endure until the castle fully collapses, they can escape.)

The cut I had made was neat, so the structure held for a while. But it wouldn’t last. If they just waited a few seconds more, they could claim victory by fleeing.

(Now then, let’s begin the countdown to collapse. Three… two… one…)

Some stared at me strangely, unmoving, but then, as the floor gave way beneath us with a deafening roar, they all turned and ran, wings flaring, to escape. Why had they come? To save the king? If he had still been alive, they would have carried him away. Truthfully, I could have killed them all in that brief moment. But that would have been too quick, too dull. So I let them go.

From today until the world’s collapse, I would eliminate as many as possible. I couldn’t waste time thinking, “That was too dull.” But this kingdom was different. I wanted them to suffer. I wanted them to die slowly. I wanted them to bear the weight of their ruler’s crime.

As I fell with the collapsing castle, I thought of that. The rubble crashing down around me did no harm. With Zygos’ power, nothing could wound me except the fall itself.

When I hit the ground, I casually flung away the debris blocking my way. Each time I threw aside a boulder, screams rang out, but I paid them no mind, hurling rock after rock. When at last I emerged into the open, armed men had already surrounded me.

“Who are you!?”
“Hmm… The Demon Lord, I suppose.”
“The Demon Lord? Don’t be ridiculous.”

A man clad in gaudy armor sneered at me. Every world had people like this, it seemed. But a man who survived the collapse of a castle without a scratch could hardly be an ordinary person.

All the better. This many witnesses were perfect for sowing fear.

I strode forward, ignoring the spears leveled against me. The man in armor barked an order, “You fool! Attack!” With a roar, about twenty men charged.

The spears reached me, but not one pierced even the surface of my skin. They simply stopped. Before the soldiers could move again, I swung the greatsword sideways. The spears the blade touched did not shatter, did not splinter; they simply vanished. The soldiers froze in shock. I stepped closer and swung again, this time aiming for their arms. As the blade touched, the arms vanished. For some, their entire bodies disappeared. As though they had never existed. As though it had all been a dream. Normally, even in death, a corpse remained. Even if there wasn’t a corpse, traces were left behind. But those struck by this sword left nothing. No body, no trace.

I hadn’t meant to go that far, but it seemed I had yet to fully master this weapon. That I would learn in time. For now, I turned to the silent, stunned survivors and spoke, “I am the Demon Lord. From this moment, I will annihilate this kingdom. Do not expect mercy. Not a single one of you will escape.”

The moment I declared it, they screamed, scattering in terror. Every man for himself, running, flying, desperate to flee. If I sprinted, I could overtake them easily. But no. I would only walk at a brisk pace. The game of tag had begun. One where being caught meant your very existence disappeared.