The undead virus, a subject Arthur had extensively researched in the world of HOTD, still held many enigmatic mysteries he couldn't fully unravel. Despite this, he had managed to grasp certain aspects amidst the sea of unknowns.

When humans became infected, they experienced an actual death before returning. This concept was rather perplexing. The virus surreptitiously altered their DNA, resulting in cellular demise. They don't divide further, nor do they require any sustenance to live after that.

Losing their rationality, completely stripped of reason, the dead are only driven by their uncontrollable instinct of eating other uninfected humans. Their bodies start to decay but that decay plateaus soon after. After their body is decayed to a certain point then even without any sort of nourishment, the undeads keep up their rather decayed form.

One could view this peculiar phenomenon as a potential advancement in human evolution if the undead retained their rationality and avoided grotesque decay.

Well, the virus removes the mental constraints on the muscles, allowing undeads to fully utilize the strength of their bodies. Once they got a hold of a normal human, it was the end of them. Their jaws are so strong that they could rip out entire chunks of flesh from the human body. They aren't hindered by injuries and are absolutely numb to pain, they boasted heightened hearing and evolved at a more rapid rate than humans.

Some could even say that undeads are super soldiers with decayed bodies and without rationality.

Perhaps the reason they seek human flesh despite not needing any sustenance to live is that it's a catalyst for their evolution...?

As for demons, the undead virus manifested intriguingly different effects.  Like humans, it brought about their passing, yet what transpired after their death was intriguing.

When demons are on their deathbed, their suppressed human memories resurface. Arthur had gleaned this knowledge from watching Tanjiro's encounters with demons with tragic backstories. Generally, they fought  Typically, they fought Tanjiro with all their might, but upon decapitation, tears welled up in their eyes. Some expressed remorse for their actions as demons, while others reminisced about unfulfilled human desires. etc, etc.

Now, once the undeads virus kills the demon and they recall their lives as humans, the virus brings back the host from the dead.

Another difference — When the demons are brought back to life, they retain their personalities. An entirely new form of mutation is witnessed in the demons. In their memories, their life as a human, as well as a demon, is stored. Their instincts underwent alterations, the compulsion to worship Kibutsuji Muzan vanished, rendering them "unowned." In that void, Arthur's Undead Manipulation skill took hold.

Thus, Arthur gained a quasi-immortal, unfailingly loyal, and rather intelligent subordinate in Ryoma.

This was one among many ponderings of Arthur's, over the daytime when he was stacking up every piece of equipment and furniture in his inventory to leave the house.

Seeing the gradually diminishing sun rays at the magic hour on the display in front of his couch, since he couldn't just stick his demonic head out of the window to check directly, Arthur yawned. It's soon going to be time to leave this town for good, he's gonna miss that ramen shop though.

Last night had proven exceedingly troublesome, completely upending Arthur's plans for the coming years... It delayed his plans to finish this mission.

Though those plans required his interference in this world much later on, at least not until the Entertainment District arc, but after that things would've ended quickly.

The reason that prevents Arthur from nuking Muzan is Daki.  If Muzan perished, all demons under his curse would perish as well, including Daki.

Now that Arthur has found a way to remove Muzan's curse from other demons, unfortunately, he can't yet use it on her. As with the ability to remove the curse on demons, he has been exposed as a traitor. Meaning, he has lost all the ways to get access to Muzan's location.

In an ideal scenario, Arthur would know the exact coordinates of Muzan, he would first turn Daki into an infected demon, releasing her from Muzan's curse, and then only a few minutes after that, he'd nuke Muzan. The progenitor wouldn't even realize anything hit him from above before he gets vaporized by the nukes.

Nuking Muzan was only possible in a surprise attack.

Also, having already battled Akaza, Arthur knows firsthand what leagues the upper moons are at. He also knows that infecting upper moons with trickery like last time doesn't work. He'll have to properly constrain them and then introduce the virus. Constraining upper moons is obviously tens of times more difficult than killing them. Furthermore, in Daki's case, it's going to be a 2v1.

To get an absolute victory against that Demonic sibling duo he's gonna need at least dozens of strong, really strong infected demons.

But...

"My Lord, I have brought your repast.", Ryoma announced, bringing a simple bowl of ramen and putting it on the table in front of Arthur's couch.

Seeing the food arrive Arthur sat up and picked up the chopsticks, after slurping up and tasting the hot ramen, he nodded, "Nice job, Ryoma, it tastes really good."

Arthur's praise brought a smile to Ryoma's face, "Thank you, My Lord"

Ryoma really was good at all sorts of odd jobs, overall he's the best servant. Cooking, cleaning, gardening, managing accounts, just name it. But his cooking seems to have really improved, he himself told to Arthur. That reminded Arthur that he had implanted the memories of cooking in him.

"Ah, yes, Ryoma. You've said that you still craved human flesh and blood, do you think you can control your urge?" Arthur asked after cleaning his mouth with a cloth.

"That is hard to tell, My Lord. But I think that even if I can control it for an extended period of time, I should consume humans on a regular basis as it increases my strength." Ryoma replied and then removed the bowl from the table. He headed to the kitchen to wash them off.

After a while, Ryoma came back with a box filled with utensils, and Arthur stored it inside his inventory.

Mentally commanding Ryoma to go unconscious, Arthur stored him inside his inventory too.

The house was now completely devoid of any sign of life except Arthur. If it was possible to store the whole house in his inventory then he would've liked it a lot but it appears that he can't, the existence of pests doesn't allow it. Arthur cannot put any living being that's emitting higher than the theta brain wave in his inventory.

Arthur floated to the hole that was created in the house last night and looked at the sky. It's already dark, but unlike last night's, today's sky was quite cloudy. The wind was noticeable too.

To save Daki, he needs to defeat her first. But even though he needs as many as possible infected demons under him for that task, he can't just go around and infect demons as he pleases. Muzan knows the location of every demon all the time. Infecting other demons is the same as sending his live location to Muzan, who knows if next time Kokushibo comes knocking at his door.

Arthur isn't sure that even escaping would be a possibility in that case.

And thus, albeit a bit bitterly, Arthur decided to not unnecessarily provoke Muzan. He simply can't afford it.

And since infecting Muzan's demons isn't an option, then how about creating your own demons and then infecting them?

With that in his mind, he shot himself to the north, to Tokyo.

=============

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