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

Chapter 16 Magic Qi Cultivation Method (Please continue reading; I'll just add the author's notes for any theories that are too long to explain)
The foundation of breathing techniques is to extract magical elements from the air through inhalation, transform them into special gaseous magical energy that flows through the meridians, and then gathers them on the blade or around the body through special techniques to form elements.

According to Urokodaki Sakonji, the main difference between the so-called schools of breathing techniques lies in the latter; the only difference between the former is the frequency and amount of inhalation, while the techniques are all the same.

Having understood the above two points, Dan Lei immediately conducted an experiment based on the magician's theory of Big Source and Small Source.

First, Danlei simply named that special gaseous magic "True Qi" for convenience, since its properties are similar anyway.

Then, Dan Lei started acting recklessly, preparing to create his own magic-based qi cultivation method.

For Dan Lei, it had become commonplace for his magic circuits to be damaged from time to time when he used magic circuits to absorb the power of the unclaimed hunting destinies around him in Luofu.

Anyway, with the healing power of Abundant Fate at hand, as long as the nutrition is sufficient and the magic circuits are not completely burned out, it will be fine after a few months of recovery.

Of course, this repeated torture of magic circuits, coupled with the dragon bloodline of the Vidyadharas, has indeed made Danlei's magic circuits much more resilient than those of ordinary magicians.

So Danlei began to use magic circuits to absorb magic power, directly penetrating into the meridians of true qi from the inside to fill them, hoping to use this method to achieve [Complete Concentration and Constant Balance].

Then, Dan Lei successfully damaged all the meridians in his body.

It's not difficult for magic power from the magic circuits to seep into the meridians of true energy, but this magic power is by no means gentle. After all, in animations, when magic power passes through magic circuits in large quantities, lightning effects are always added.

Therefore, Dan Lei's meridians, which he had hardly ever trained, were instantly damaged, even affecting his magic circuits, causing him to spit out a mouthful of blood.

Fortunately, he received treatment from the abundant energy, and his life was saved.

Later, Sasaki Kojiro obtained two old ginseng roots for the reckless Master, and Dan Lei was able to use the medicinal power to completely repair his meridians.

After his one reckless act, Dan Lei dared not be so reckless again, directly allowing the magic power in his magic circuits to enter his meridians.

So Danlei changed his target, using the magic power of the magic circuit to enter his lungs and try to convert magic power by changing the magic particles in the air to enhance his true qi.

As a result, this experiment was half successful.

While the magic power from the magic circuit can indeed be converted into true qi when it enters the lungs, the efficiency is simply appalling.

Because the magic stored in the magic circuits was refined by Danlei, its quality is much higher than that of magic particles in the air.

The Danlei breathing method is only for beginners. It's like asking a baby who can only drink milk to absorb meat; indigestion is the least of your worries.

However, with the power of abundant destiny, ordinary injuries are no problem for Dan Lei.

Moreover, Dan Lei inadvertently learned a method of breath-holding in this experiment. He could produce oxygen when converting magic energy into true qi in the magic circuit. As long as the carbon elements stripped off did not exceed Dan Lei's tolerance limit, he could hold his breath for a long time.

Of course, this ability is actually quite useless to Dan Lei. The Cloud Chanting Technique of the Chiming Clan originally has a secret method of breathing underwater, so even if a member of the Chiming Clan does not know the Cloud Chanting Technique, as long as someone guides them, they can still enter the Scale Abyss Realm to transform into an egg and be reborn.

As for the universe, theoretically, as long as a Destiny Walker is strong enough, they can obtain all the energy their body needs from the imaginary energy of destiny.

Those who can physically enter the universe are all beings who envelop their bodies in a protective aura of destiny energy, shielding them from all cosmic rays and pressure differences. The energy their bodies need is then provided entirely by this destiny energy, allowing them to fight in space without any protection.

Of course, this has nothing to do with Dan Lei. As I said before, Dan Lei has not studied the Abundant Destiny properly. Although he has been making progress by constantly pushing himself, he is still far from being able to directly go to the universe with his physical body.

Therefore, after half a year of hard work, Dan Lei came to the conclusion that haste makes waste, and he needed to solve the problem of improving the efficiency of converting magic energy in his lungs before he could continue to study the magic energy cultivation method.

So how to enhance the efficiency of converting magic power in the lungs? The answer is simply to diligently practice breathing techniques. Fortunately, Dan Lei hadn't wasted the past six months of hard work; his lungs, now practically made of iron, would progress by leaps and bounds once he began practicing breathing techniques.

At this time, Tanjiro was still training his agility and practicing his swordsmanship.

Of course, even without training in agility, Danlei still can't escape being swung at.

Moreover, Sasaki Kojiro personally supervised Danlei and Tanjiro's sword-wielding practice. Now, besides fishing and catching demons, he spends all his time watching the two of them wield their swords. If they make a mistake, he will hit them directly with a tree branch and correct their movements.

Yes, Sasaki Kojiro's job also includes catching demons, and while Dan Lei was busy experimenting with magic-based breathing techniques, he didn't forget to continue researching the demons and Nezuko's ability to absorb ley line energy.

At night, while Tanjiro is studying his academic subjects and writing in his diary, Danrui will go and bother the demons that Sasaki Kojiro has captured.

Given Sasaki Kojiro's strength, he might not be able to defeat the Upper Moons now, but he would definitely be able to instantly kill the Lower Moons and other demons.

Since it is known that the abilities and activity levels of demons are actually linked to magic power, Dan Lei only needs to create a box that can seal magic power. Sasaki Kojiro can then cut off the demon's limbs, stuff them into the box, and bring the demon back in a sealed state.

Lower Moon demons are not easy to encounter, and the few Danlei who know their location don't want to take them down right now. So, the information about the demons is actually provided by Urokodaki Sakonji, and whether or not they have Blood Demon Art depends entirely on luck.

However, this does not affect Dan Lei's research. Anyway, there is no need to be humane with ghosts, so he can do whatever he wants.

Urokodaki Sakonji also agreed with this point, and later became Tanrei's assistant in his research on demons.

So, Dan Lei quickly confirmed through more than a dozen ghosts with the talent of Blood Demon Arts that Blood Demon Arts is indeed an awakened ability of ghosts, something innate and cannot be imitated.

Because all demons with blood demon magic have unique and independent internal differences, and may even grow corresponding organs directly for their abilities, Dan Lei doesn't want to transform himself into an alien. These organs are just recording the trajectory and structure of magic power.

However, Dan Lei has already made some progress in his research on the absorption of earth vein energy by ghosts. After a large number of comparative experiments, Dan Lei has been able to reconstruct the energy absorption model by observing the fluctuations of the earth veins absorbed by ghosts.

In addition, Nezuko had already fallen into a deep sleep and began to absorb a large amount of ley line energy to complete her evolution. With real-time data, Danlei naturally improved the model and reconstructed the demon's ley line energy absorption matrix.

Next, all you need to do is create a magical item using this matrix and wear it. This item doesn't absorb a large amount of ley line energy, but it's durable. Wearing it continuously can shorten the Holy Grail's charging time by at least three to five years.

The best materials for this magical item are those from oni, but Danlei found those man-eating oni disgusting, so he simply plucked hair from Nezuko's sleeping head to make it.

Of course, Dan Lei asked Nezuko for her opinion when he cut her hair, and she did not object.

Tanjiro objected, but his objection was ineffective. In the end, Danlei used Nezuko's hair as a medium and combined it with a magic absorption array to make a waist pendant, so that it could continuously absorb energy from the ley lines, at least in this world.

　Mana, as the life force of a planet, manifests itself in the form of leyline energy (such as the spiritual veins of Fuyuki City).

　　Magic particles in the atmosphere
　　Life fluctuations generated by natural cycles (in a typical case, during the Fifth Holy Grail War, Rin Tohsaka replenished her mana through ley lines, absorbing approximately 2000 units of mana per hour).

　　This energy is similar to the concept of "spiritual energy of heaven and earth" in the cultivation system, and it needs to be transformed and used through a specific magic base.

　　Od, as the life energy within organisms, has the following characteristics:
　　The average human naturally produces about 10-50 units per day.
　　Magicians can store 300-3000 units (depending on the quality of the magic circuit) through their magic circuits. Excessive consumption can lead to organ failure (as seen in the case of Matou Kariya).

　　The setting is highly similar to the operating mechanism of "internal energy" in martial arts novels, both requiring transmission through specific meridians (magic circuits).

　　However, aside from natural biological growth or finding ways to advance one's life form (by fusing with the bloodlines of mythical beasts or magical beasts, or becoming a high-ranking Dead Apostle), Type-Moon Genji can hardly increase his quantity through cultivation (the improvement from physical training is negligible). He can only continuously optimize his usage efficiency. (A typical example is Aozaki Touko.)
　　
　
(End of this chapter)