Preliminary Report on the Combat Power of Pillars and Ghosts

Dan Lei, Tanjiro, and Giyu Tomioka's sunrise viewing went off without a hitch.

Tanjiro and Giyu spent the whole time listening to Dan Lei describe the outside world, while Dan Lei simply repackaged the magecraft world of the Nasuverse as stories to tell them.

Since almost everything was based on real people and real events, Tanjiro's nose didn't catch even a whiff of a lie from Dan Lei. Giyu even remarked that if he ever got the chance to retire, he'd definitely go abroad to see for himself.

In the end, the deer Dan Lei had caught for bloodletting and drawing the Heroic Spirit Summoning Circle wasn't wasted. Dan Lei had Kojiro Sasaki carry it to the mountaintop, where it became the trio's breakfast.

Bathed in the light of the rising sun, Giyu Tomioka completely let his guard down toward Dan Lei, who stood in the sunlight. Before leaving, he pulled out a section of bamboo from who-knows-where, fashioned it into a muzzle, and gave it to Tanjiro, telling him to use it to keep Nezuko's mouth shut so she wouldn't suddenly lash out and bite someone.

Of course, given bamboo's strength, if Nezuko really wanted to bite, she could shatter it in one go. This thing was essentially a deterrent for the law-abiding, not the lawless—more for show than actual purpose.

After handing over the gift, Giyu took his leave. As a Hashira, he was quite busy, and this encounter with Dan Lei required him to write a report for his teacher and the Demon Slayer Corps' Master.

Parting ways with Giyu Tomioka, Dan Lei and Kojiro Sasaki followed Tanjiro toward Sagiri Mountain.

Since it was the Taisho era, Dan Lei only had a vague grasp of the land beneath his feet—just a rough idea of place names.

As for how to get from the mountain where Tanjiro's home was to Sagiri Mountain, Dan Lei admitted he couldn't make heads or tails of the map, which looked like a mess of ghost scribbles. Even Kojiro Sasaki was better at navigation than he was.

So, Tanjiro took the lead the whole way.

Just as Dan Lei had predicted earlier, there were very few things in this land that could cultivate using Ley Lines, but demons could naturally absorb Ley Line mana.

After several days of observation, Dan Lei confirmed that Nezuko, even when not asleep, could slowly absorb mana from the Ley Lines just by standing there, replenishing herself.

When she slept, it accelerated her absorption of Ley Line mana.

Thus, with almost no energy expenditure from movement, she could balance the energy deficit within her body during the early stages of becoming a demon, suppressing her urge to feed.

After all, the reason demons crave human flesh is that the mana contained in human blood and flesh is richer than in rare creatures like phantom beasts or magical beasts.

Human blood being the easiest high-quality magical medium to find is basic common sense. Countless cult magical rituals explicitly state that the best medium for drawing ritual circles is human blood.

And the human instinct to eat is etched into DNA. So when a demon's body lacks energy, it naturally wants to feed, and mana-rich human flesh and blood are the best food.

As for why demons find ordinary food disgusting after turning, it's likely the same reason someone used to heavy flavors finds bland food unbearably tasteless.

Once ordinary food is processed, even ingredients that originally contained mana have it destroyed by high heat. Without mana to season it, a demon eating it feels like chewing on wax.

Demons that rely on long-term feeding to replenish mana naturally let their ability to absorb Ley Line mana for sustenance atrophy from disuse. That's why Dan Lei found the Ley Line energy here abnormally abundant.

However, all these conclusions were drawn by Dan Lei from observing just one demon—Nezuko—lacking controlled experiments, so their accuracy remains up for debate.

Of course, in his spare time, Dan Lei also used telepathy with Kojiro Sasaki to align their assessments, estimating where a Hashira like Giyu Tomioka would rank among Heroic Spirits.

Well, it's better not to compare Giyu's combat power to Heroic Spirits. According to Kojiro Sasaki, if Giyu's stats were placed among Heroic Spirits, Luck was unknown, but Strength and Agility might be D, and the rest would likely be a string of E.

That combat power isn't weak by magus standards, but among Heroic Spirits, he'd probably only be able to fight one of the Hundred Personas' maximum-number clones.

Of course, that's assuming that clone doesn't use poison and fights head-on.

From this perspective, the Lower Moons, who are roughly on par with or slightly weaker than ordinary Hashira, should be at this level too.

You ask what level Dan Lei is at among Heroic Spirits now?

Dan Lei would tell you that his Strength and Agility are around E+ (using Reinforcement Magecraft can spike these two stats); his Endurance, with the blessing of the Abundance Destiny, can likely reach C; his Mana, in the environment of Demon Slayer: Kimetsu no Yaiba, is at least B; and his Luck—well, he managed to cross worlds, so it must be A.

But don't let Dan Lei's high stats fool you. In a real fight, if he gets closed in on, he might not actually beat Giyu Tomioka. That's a gap in technique. After all, Dan Lei currently has a ton of mana but knows very few combat-specific spells, and his martial arts are mediocre. In a fight, he can only bully the weak.

But as a support and healer, Dan Lei is absolutely professional. The medical knowledge Dan Zhu taught him hasn't been returned to her, the Abundance Destiny's healing is top-notch, and he can also make puppets for backup.

Ultimately, though, a demon's strength lies in its Blood Demon Art. These arts are often unreasonable, and even a Hashira can trip up against a particularly nasty one.

In this regard, demons are stronger than Dead Apostles. With Dead Apostles, at low levels, you'd have to analyze the specifics to compare their combat power to zombies. They don't get innate abilities until they reach high-tier Dead Apostle status.

But demons seem to naturally awaken Blood Demon Arts after eating just a few humans.

Combined with the fact that Nezuko awakened a Blood Demon Art without eating humans, Dan Lei analyzed that this might actually be a blessing from the Ley Lines.

Evil demons being a species blessed by the Ley Lines—that joke is too dark. So Dan Lei just silently noted it, planning to verify it later.

After several days of traveling day and night, Dan Lei's group finally reached the foot of Sagiri Mountain, and Dan Lei found his first controlled experiment subject.

It was still the temple from the anime, but this time, before Tanjiro even got close, Dan Lei used magecraft to hear the disgusting chewing sounds inside.

Since there were no living people left inside, Dan Lei didn't stop Tanjiro from approaching and opening the temple door, wanting him to witness a demon eating humans and realize the horror of these monsters.

Seeing the hellish scene again, Tanjiro was indeed stunned.

But when the demon lunged at him, Dan Lei made his move.

He used magical threads again. As the foundation of puppetry, Dan Lei was most skilled with them, and against ordinary demons that couldn't use Blood Demon Arts, their strength wasn't enough to break free from the threads' binding.

So the demon was frozen mid-lunge, suspended in the air by the magical threads.

Then Dan Lei shoved past Tanjiro, who was blocking the doorway, looked at the evil demon inside, and smiled.

"Alright, the experiment subject, deserving of death, is captured. Now comes the fun part—experiment time.

Tanjiro, go dig a few pits behind the temple and bury these bodies. My experiment here is going to get a bit bloody, so it's better if you don't watch."

Honestly, the original Fate setting where Heroic Spirits always dominate magi is just a fantasy from today's perspective.

Not counting beings like True Ancestors, there are already several magi whose combat power rivals Heroic Spirits.

And Medea got beaten down in close combat by Rin in the UBW route.