Liera tilted her head. Yu IlHan momentarily couldn't breathe after looking at her beautiful face, but, as always, he hypnotized himself into thinking that 'Liera is a sister-like being' and continued speaking.
"Backdoors refer to program codes that the developer puts in order to access an operating system or an application more easily. Let's say that there's a backdoor on my computer. Although I usually have to enter a password to access my account, the developer can access it without any identification, even remotely. It literally is a 'back door'."
[That's a thing bad guys use!]
"You're right. Although it's not really made for evil purposes, the concept is like that."
[...But why does that word come up here?]
"Well, then. Think about why I would have mentioned such a word at this time."
Liera colored in doubt. Yu IlHan gave her a little time to realize it herself, and his expectations were not betrayed as her face coloured with shock.
[You, don't tell me...!]
"It's exactly that."
[You scammer!]
"It's quite satisfying to hear that from the original scammer."
What was there to hide? Yes. During the 2nd Great Cataclysm, Yu IlHan had tinkered with all the Traps of Destruction that were to be scattered on Earth!
However, what was more amazing was not that he tinkered with them, but that none of the higher existences realized it.
Liera found it absurd that she and the other angels had been completely fooled by him, but Yu IlHan only explained proudly, without knowing how she felt.
"I put a little more effort in since I don't know when and where something weird would happen. You guys didn't know when I mixed dragon tongue and ancient elven language."
[That's no different from the methods that the fallen angels used!]
"But here's a situation where I'd need it, no?"
[Eeeek.]
Liera had a lot to say, but she couldn't say anything.
He was right. Earth, in the end, had fallen into a situation the Heaven's Army could not predict, and if Yu IlHan had installed backdoors or whatever on the Traps of Destruction and if it helped out in this situation, then she could only accept it.
"I need to dig my own hole in order to survive."
[Ugh, why is the Heaven's Army so useless...! However, if they were capable, then IlHan would have a hard time since he wouldn't be able to make backdoors, but wait, if we were capable, then there doesn't need to be such situations in the first place…..]
Yu IlHan left Liera to her endless cycle of bad thoughts and lowered the flying fortress's altitude. To use the backdoor, he needed to get closer to the ground.
[Krrk?]
[Kuhooh!]
When the flying fortress showed itself below cloud level, the monsters that noticed the gigantic shadow all looked up at it.
However, Yu IlHan didn't even care about the wingless monsters. If there were many of them, he would have gone into battle after landing at the fortress, but there were too few right now! What he was looking for were dungeons that could solve the problem of insufficient monsters on Earth right now.
"Oh, there's one there."
Yu IlHan's eyes glistened. Not far from the flying fortress, a dungeon-specific vortex was visible. Moreover, a faint aura emanating from the dungeon's core regions was proving it was Yu IlHan's own doing.
[Huh? But IlHan.]
Liera, who escaped the endless cycle, raised her head. She realized she had forgotten the most important thing.
[And so? What is the utility of this backdoor?]
"I couldn't add that many. Well, I can see what kind of monsters are inside and in what numbers."
[That's good! Even I don't know what's in the dungeons on Earth. That's just like navigation! So it's not that much different from what we informed you until now.]
Liera's expression brightened. It looked like she could accept that much. Yu IlHan giggled, thinking about how honest she was and how she was almost unable to lie.
But what could he do? That was just the foundations required to implement the 'most important utility' of the backdoor.
Yu IlHan added while giggling.
"And a function to make dungeons explode."
[....Huh?]
"I said there is a function to make dungeons explode."
Yu IlHan knew how Liera felt, so he explained in kind. She stared at him in a daze after hearing that, then shouted, eyes wide.
[Why did you put such a function in it!]
"Although there's a lot. I could use it as a threat when the people of other countries are trying to threaten the ones close to me."
[That's just terrorism!]
Liera was angry that Yu IlHan had created a function that could potentially harm civilians. However, he only shrugged.
"Even I don't want to harm civilians. It's just a backup method. Carrying it out is a big problem. But you know it as well, don't you? Think about the position that Vanguard holds. If I didn't have such a card in my hands, it would have been worrying."
[That's... true.]
Even before the 2nd Great Cataclysm, the value of Vanguard was incomparable to all others. If those in authority and power had malicious intent, they could have extended their hands to his friends and family, even if they couldn't do so to him.
And in truth, no big problems occurred thanks to the cooperation with Kang MiRae going smoothly, but Yu IlHan couldn't be criticized for making backdoors just in case. Liera knew that, so she could only sigh.
"And also."
Just as Liera accepted the situation a little, Yu IlHan added.
"If I use this, I can fight against a large number of monsters at once. It's also advantageous for me to bring them out here instead of me going in."
[Sheesh, your scale is too big to be measured using a scale at all.]
Of course, Yu IlHan wasn't going to mention anything about the backdoor at all if he didn't need to. If it came to the worst, he was going to take on the role of cleaning all the dungeons while travelling the world.
However, the people of Earth endured the 2nd Great Cataclysm even without him interfering. No, with the gates to other worlds opening, the situation developed at a speed beyond his imagination, and stabilized as well.
Even he himself, who had prepared everything in advance, was working elsewhere, so there was no need to use it. However, just as everything seemed to be coming to an end, the 3rd Great Cataclysm occurred, upending everything. Although, just speaking of the result, it was a good outcome for him.
[And so? What are you going to do now?]
"Make dungeons explode, of course."
[So you mean to say, since there are too few monsters on the land, you want to supplement them using the monsters inside the dungeon?]
"Exactly."
Yu IlHan's willpower was like steel. He was no newborn baby and knew the dangers of detonating dungeons. Liera gave up trying to persuade him.
[Gosh, I don't care anymore. Do whatever you want.]
"In fact, you don't have to tell me; I was already going to do it!"
The moment the flying fortress skipped past a dungeon gate, Yu IlHan called out a small artifact he had made using a 2nd-class magic stone and dropped it onto the gate.
The magic stone dropped rapidly and landed on the gate, and without exaggeration, the gate exploded with a 'boom' in the very next moment!
[Kihaaaaa!]
[Freedom! I'm free!]
[Kill humans! Let's earn records!]
[Kill, kill!]
In an instant, a monster army numbering a hundred thousand rushed out into the region. As this was a dungeon maintained since the 2nd Great Cataclysm, over 70% of them were merely 3rd class, but Yu IlHan did not care. They would soon be promoted to 4th class. The current Earth was just that insane.
Yu IlHan realized something and stopped thinking about the monsters' insane growth.
"Perhaps the people of Earth may not be able to survive even if they came back."
[That's a coincidence. I was also thinking that. But right now, I don't think you are in a position to care about other people.]
"That's true. Let's move a little quicker!"
[That's not what I meant, idiooooot!]
Yu IlHan, who had quickly detonated a dungeon, drove the flying fortress to detonate other dungeons as well. Even more of a headache was that the monsters from the dungeons Yu IlHan had freed also had the power to make other dungeons explode!
[Hey, this is completely a dungeon wave! To think you'd cause an artificial dungeon wave... This is usually a disaster that's at the top of the food chain in terms of disasters for a world!]
"Good, fill the Earth with monsters!"
[You are scary when you act like a villain like that, so stop it!]
Liera didn't lack this, but Erta was better at retorts. – Yu IlHan thought about that and licked his lips. He didn't want to show he missed Erta, so he sped up the flying fortress wordlessly.
The world was wide, and there were plenty of dungeons. Yu IlHan's Traps of Destruction could propagate backdoors to other Traps of Destruction as well, so right now the only dungeon Yu IlHan couldn't make explode was the hellish dungeon he had escaped before.
[What about the aerial dungeons or the oceanic dungeons?]
"I need to open all of them too. The fortress is prepared for battle whenever and wherever the battle may be."
[Uaaaah, it's not like the Traps of Destruction are completely destroyed just because a dungeon was opened, but if that happens, an Overflow will happen....!]
"That's exactly what I want!"
The flying fortress was not as fast as Yu IlHan with his Ruin Calling, but its maintainability and flight stability were incredibly high for a fortress of its magnitude.
On top of that, Yu IlHan was throwing artifacts like he was tossing toys, and whenever the fortress passed by a dungeon, they were hit by these artifacts and freed tons of monsters, as if a chick were being born from an egg.
[It's an Overflow, an Overflow!]
"Oh, there's a dungeon in that airspace there too."
Once he had planned the collapse of the dungeons, Yu IlHan didn't know when to stop. Since many monsters were popping out at once, the monsters that didn't usually fight each other grew tense, and when the mana current was twisted, the records of monsters fused, giving birth to a freakish new monster. This was none other than the signs of an Overflow.
"Wow, 4th class monsters are being made real-time..."
[Even if you say it like chicks are being born from eggs, it's a horrible sight!]
Yu IlHan smiled in satisfaction, seeing the Earth colouring in chaos, like the initial stages of the 3rd Great Cataclysm, before asking Liera, who looked as if she had given up on everything again.
"How is it? Earth's growth will be accelerated, right?"
[If, and only if, the enormous amount of mana possessed by the monsters returns to Earth and forms a cycle.]
"Aha, that's my field of specialty right there."
He replied confidently and extended his hand to grab the Eight-tailed dragon spear. When Yu IlHan swung it like a conductor would in an orchestra, the Hundred Eyes, which had been in standby mode, all began to activate.
A hundred destruction mirrors rose into the air, one after another. And a frightening amount of mana gathered around them – the weapon that would call forth equal fear and despair in all aimed at the ground.
[Kiiiii?]
[It's still bright, but I see the moon.]
[There are a lot of moons. They're shining brightly.]
[There's a human up there. We need to kill!]
Yu IlHan had destroyed so many dungeons in that short time that the number of monsters drawn to the flying fortress and gathering in the area easily numbered over a million! There were quite a few 4th-class beings who had just been born, which made Yu IlHan smile.
"Well, then."
He raised the Eight-tailed dragon spear and swung it, shouting.
"Fire!"
Rays of light numbering one hundred connected the sky and the ground in straight lines. The unlucky monsters in their paths were all burnt to black ash.
The monsters roared at the sudden, unexpected disaster, but the retribution of light continued until all the monsters in the region died and until all the monsters beyond the region died.
It took a mere 3 months from the time all the dungeons on Earth were freed to the time they were all decimated by Yu IlHan.