Here's a small piece of knowledge that Li Mo only learned later - the origin of the term "deus ex machina."
In theater, specifically in ancient Greek drama, when the plot reached an impasse and couldn't progress, they would introduce a powerful, previously unseen god using mechanical devices to appear on stage and resolve the problem.
Li Mo felt he was like that "deus ex machina" god.
Though not particularly powerful himself, he had to help them overcome certain death situations.
But... wasn't this actually fine?
So what if it's deus ex machina? As long as the ending turns out well, what more could one ask for?
He gazed at the sky.
Batch after batch of youkai soared into the heavens. Their leaking power interconnected, blotting out the starlight.
That full moon, that moon bathing everything in silver light, became surrounded by the mist formed from the youkai. The stars encircling the moon were obscured by the demonic fog, leaving only the central circular area where moonlight could still pass through.
Under his watchful eyes, the demonic mist gradually closed in, sealing even that last gap. Finally, no more moonlight could shine through.
Tonight was both a night of the full moon and a moonless night.
Using his own power to block out the moon hanging in the false sky - how joyous this made them.
Even Li Mo, standing on the ground in his celestial fox true form, could feel that joy.
For most youkai, the "Hyakki Yagyou" was a grand gathering.
An occasion to freely display their power and indulge their wildest desires. Moreover, since this was their final revelry, who would want to hold back?
"Aren't you going up to join the revelry, Hakushin?"
"This old one's age counts as elderly even among youkai. I'll refrain from carousing with the youngsters for now."
"You're already dead - what does age matter now?" Li Mo responded.
Echoes of the deceased - this was the current state of these youkai. They weren't even proper spirits anymore. After being tainted and dragged through the ley lines, then passing through the Sacred Sakura's roots, even Li Mo couldn't be certain of their exact condition.
Hakushin asked, "So you're still not confident about reviving old ones like me?"
"Nothing in this world is one hundred percent certain," Li Mo said. "When I act, I don't calculate chances of success first - I consider failure first."
Since the world of Demon Slayers, he'd always prepared escape routes. Even if never used, those escape routes remained available.
Hakushin pressed, "Then what would you estimate your chances to be?"
"About ninety percent. More precisely, ninety-five percent. The remaining five percent I leave to fate."
"Good, that's practically certain success." Hakushin laughed. "No wonder you get along so well with that little Miko girl. Your personalities are nearly identical."
Both had a habit of making unimportant, non-urgent matters sound critical and tense.
This trait was exactly like Yae Miko's.
"Ah, I wasn't like this before. That Miko girl is a bad influence."
"Is that so? Young man, this old one has a question for you - why are you helping beings like us? To achieve that ninety percent certainty, you must have exerted tremendous effort?"
"Hakushin, you underestimate me. 'Tremendous effort' is an exaggeration. Your situation isn't that difficult to resolve," Li Mo said dismissively.
"Your stubbornness is also identical to that Miko girl's."
With that, Hakushin soared into the sky to join the revelry.
Li Mo closed his eyes. "Hakushin, that comparison feels wrong."
How could I possibly be like Miko?
I'm clearly the good guy here.
Moreover, the revival ritual wasn't particularly difficult. Rather than true resurrection, it was more accurate to call it reincarnation.
Li Mo's plan was to have them reincarnate. He would create new bodies for them, completely unrelated to their original forms. One might even say that from this moment onward, these youkai would become an entirely new species.
Creating new bodies required templates. Starting from scratch to create a new lifeform was something only an omniscient, omnipotent creator could do - far beyond Li Mo's capabilities.
But Teyvat had a peculiar phenomenon - ley line blossoms spawning monsters. As Li Mo had explained to Lumine, there were two possibilities: either the blossoms attracted existing monsters, or they actually birthed new ones.
Monsters often appeared immediately after interacting with ley lines.
Thus, one could consider that ley line blossoms spawned monsters. And ley line blossoms themselves were born from accumulated ley line energy.
Ignore the process, and the conclusion remains:
Ley lines spawn monsters.
"What we call 'mystery' is like using similar conditions to perform analogous processes and achieve identical results."
This was Li Mo's unique understanding of mystery.
He raised his hand, extending his perception outward. Leaping down from Grand Narukami Shrine, he used soldiers created from "Shadows of the Dragon" as stepping stones, spreading his awareness across all of Mt. Yougou.
The stats on his system interface could no longer reflect his true power. While the numbers appeared to hover at peak human levels... when enhanced by "Mystery," all attributes soared to terrifying heights.
Mt. Yougou lay within his sight, and thus all its ley lines fell under his influence.
The ley lines contained not just energy, but also corruption. Even with the Sacred Sakura constantly purifying it, the corruption in the ley lines couldn't be completely eradicated. Deep underground, at unfathomable depths, lurked the source of this corruption.
But no matter how severe the corruption, it was useless against Li Mo.
He was the greatest corruption of all.
"All the World's Evil" originated from a Servant named Angra Mainyu, who bore the concept of "all sins."
Li Mo was the same.
When two corruptions of the same caliber met, how could one contaminate the other? The uncontrolled corruption became like snacks to Li Mo.
Thus, Li Mo had long since surveyed all the ley lines of Mt. Yougou. Using "Shadows of the Dragon" as extensions of himself, he set up rituals throughout the area. Now, as the rituals activated, ley line energy flowed into his body in a peculiar manner. After circulating through him, its symbolism was redefined before flowing back out.
Ley line energy carried the taint of corruption. Using it directly to create bodies for the youkai might curse them like the Hilichurls. Therefore, he purified it through his own body.
The dual concepts of "All the World's Evil" and "Human Evil" didn't belong to any negative category.
A new layer enveloped the shrine priest's form.
A radiant white garment like the purest moonlight.
As more energy gathered, this outer layer expanded, transforming until it resembled a giant fox.
Li Mo ascended, flying upward toward the heavens.