They won the Holy Grail War, but this turned out to be the Virtual Tree Universe.

Chapter 13 All Ineffectiveness Stems from Insufficient Firepower
After spending these days together, Tanjiro still listens to Danlei's words.

After all, as a "wild man from the deep mountains" during the Taisho era, Tanjiro said that anyone in the vicinity who could read could call themselves a cultured person.

With Dan Lei's knowledge, he must be at least a PhD level. Moreover, Dan Lei would occasionally teach Tanjiro some physics tips to increase his favorability, and he even taught him multiplication tables, making Tanjiro almost regard Dan Lei as his master.

So, since the demon had been immobilized by Danlei, Tanjiro very conscientiously took Nezuko to the temple's backyard to find tools to dig a hole.

Dan Lei, with a strange laugh, moved the unknown ghost to the outer courtyard, pondering where to strike it.

However, this ghost was a chatterbox; even after being captured alive, it kept talking.

"Hey, what's wrong with you? What kind of sorcery did you use to subdue me? Are you one of those legendary ghost hunters? But why does your aura feel so strange? It's not human!"

Dan Lei never expected that one day a ghost would say he didn't look human. So, he decisively waved his hand, and a sharp ice blade appeared in his hand. He cut off the ghost's head and hung it alone on a tree to the side.

Even after doing that, the ghost kept babbling on and on.

So, Danlei took out the paper and pen he had made using magic tricks to write down his thoughts.
"The moment the head is physically severed, a small airflow system is rapidly constructed in the damaged throat, proving that ghosts can indeed consciously generate or modify the organs inside their bodies."

"The bleeding after the head was cut off lasted for less than three seconds. The amount of bleeding was not too large. Its self-healing ability is stronger than that of ordinary Dead Apostles. It belongs to the level of high-grade Abundant Beasts."

After finishing, Dan Lei casually cut open the ghost's chest and abdomen to expose its internal organs, and then made a note of it.

"The heart is beating, but it is black. The tissue structure is clear. There are black unknown patterns on the esophagus and stomach, which are speculated to be growing in order to effectively enhance the absorption and conversion of magic power in the flesh and blood."

Even if the ghost's head was no longer on its body and it couldn't feel pain, Dan Lei's actions would still send chills down its spine.

After all, even if an intelligent being knows it won't die from watching itself being disemboweled, it will still feel fear.

However, without the threat of death, fear is not amplified. This demonic transformation directly turns fear into anger, and he begins to curse and swear at Dan Lei.

Danlei's response was simply to completely seal the air vent under its neck and all the holes on its head with ice. In this way, without airflow, no matter how wide it opened its mouth, it couldn't make a sound.

After finishing, Danlei even lifted its skull, looked at the still-living brain inside, and decisively used an ice blade to lift it, freezing the brain and throwing it on the ground.

The ghost, which had been moving just moments before, stopped moving instantly after its brain was pulled out. It stopped struggling, but soon a new brain grew out of its skull, and even the top of its head grew out on its own.

So Danlei recalled those ghosts in the story whose heads grew directly from their bodies and made notes.
"Removing the brain can temporarily halt all of the ghost's actions, but it will quickly regenerate a brain, and it doesn't necessarily have to grow from the head area again."

Since this demon is of a very low level, you can't find information about Blood Demon Arts on it.

Moreover, after this guy's brain grew back, his IQ seemed to have increased as well. Two arms and hands grew directly from under his neck, and he started to remove the ice on his head. After clearing the air from his ears, he started cursing Danlei again.

Seeing this, Dan Lei decisively used magic thread to bind the ghost's two small hands again, then resealed the hole to silence it, and cut off one of the ghost's legs, wanting to see the true killing power of his magic against ghosts.

After a flurry of fireballs, lightning bolts, and ice spikes, Dan Lei realized that his ordinary elemental attacks were insufficient to completely kill all of the ghost's cells.

To kill a ghost using this method, you can only injure it to the point where its internal energy is depleted to the point of being unable to heal itself; otherwise, you will have to face an infinitely multiplying physical body.

At that moment, a person suddenly emerged from the woods and slowly said...
"This method alone is not enough to kill the demon."

This person is the target that Danri and Tanjiro are looking for this time: Urokodaki Sakonji, the former Water Pillar of the Demon Slayer Corps.

He arrived while Dan Lei was performing brain surgery on the demon, and the spirit-formed Sasaki Kojiro immediately informed Dan Lei. However, Dan Lei instructed Sasaki Kojiro to remain vigilant and not to worry about him, which is why he has been able to see until now.

In response to Urokodaki Sakonji's words, Dan Lei silently drew a magic circle with the demon's blood and then cut off a fresh leg and threw it in.

The magic circle activated in the next second, and the leg instantly turned to ashes and disappeared.

So Dan Lei smiled at Urokodaki Sakonji.

"It's not that complicated. Monsters like ghosts still follow the law of conservation of energy. Once their magic power is drained, their bodies will immediately dissipate."

Of course, this ghost was also too weak; its physical body's energy binding efficiency was extremely poor, and the amount was small, so it was drained dry in one go.

After finishing, Danlei turned to the ghost's body again and said...
"Actually, the elements are not entirely helpless against ghosts; all the ineffectiveness stems from insufficient firepower."

After saying that, Dan Lei added some more ghost blood and drew a magic circle under its body, and a blue-white flame shot out.

This is the magic circle that Orange taught Danlei to use to melt metal when making puppets. In his previous life, Danlei could only raise the flame temperature to over 800 degrees Celsius, which was the limit. Orange was the only one who could complete the metal melting work for many high-level puppets.

But now, Danlei instantly raised the temperature to 2000 degrees. Although this would consume a lot of his magic power and wouldn't last long, it was enough to show off.

The ghost's body instantly vaporized at 2000 degrees Celsius, and its bones rapidly carbonized into a completely lifeless object.

At this moment, Sasaki Kojiro appeared on Danlei's orders and threw the demon head hanging on the side directly into the flames.

As soon as the ghost's head was burned, the ghost died instantly, and even the brain that had been frozen in front of it on the ground turned into black ash.

After finishing, Danlei extinguished the flames of the magic circle, and then spoke again to Urokodaki Sakonji.

"Look, this way we can burn the ghost to death directly."

Furthermore, if one could summon real heavenly lightning, the ghost would surely be struck dead.

"Furthermore, I've just tested it and found that elements can effectively reduce the number of cells that kill demons and weaken their defenses. The reason your breathing techniques, which imbue swords with elements, are more effective at killing demons is based on the same principle."

At this moment, Urokodaki Sakonji was already drenched in sweat. If it weren't for the mask on his face, Dan Lei would have been able to see the corners of his mouth twitching constantly.

After a long silence, Urokodaki Sakonji came to his senses and bowed slightly.

"Urodaki Sakonji met with his foreign friend, Lord Tanrei, and Lord Sasaki Kojiro."

Yoshiyuki Tomioka has already told me about the two of you; you are truly extraordinary individuals.

Mr. Danlei's ability to burn ghosts with divine flames left me speechless.

Sasaki Kojiro is a powerhouse at the Celestial Realm; I, in my old age, am ashamed to admit my inferiority.

　This phrase, "preventing the ghost from making a sound," is equivalent to deliberately blocking the throat with the back of the tongue, so that no sound can be produced.

　　
　
(End of this chapter)