Breathing Technique's Mana Refinement Method Doesn't Need Magic Circuits

Chapter 15: Breathing Technique = A Mana Refining Method That Doesn't Require Magic Circuits

From Sakonji Urokodaki's perspective, Dan Lei had the martial arts of a Celestial Realm powerhouse at his fingertips, yet he came to learn Breathing Technique from him instead—it was like abandoning a gold mine at his feet to dig for copper ore in these deep mountains. Even the saying "throwing away a watermelon to pick up a sesame seed" couldn't fully describe this behavior.

After all, Giyu Tomioka's letter made it clear that this Kojiro Sasaki could probably take him down in just two strikes.

And after Sakonji Urokodaki met Kojiro Sasaki, he figured that if it were him, he probably couldn't even block one.

Because along the way, Sakonji Urokodaki had used all his strength and still couldn't detect his presence, yet Dan Lei would just wave a hand or call out, and the man would instantly appear beside them.

This gentleman could show up in broad daylight, had a shadow under the sun, and though he was a bit quiet, he could still respond normally when Dan Lei spoke to him—so there was no way he was a demon.

In Sakonji Urokodaki's understanding, if he wasn't a demon, he had to be a living person. His inability to detect the man was simply an absolute gap in cultivation level, since he himself could do something similar to ordinary people.

However, Dan Lei wanted to learn Breathing Technique not for the swordplay within it, but to personally experience the feeling of cutting out elemental attacks through breathing, so he could understand its principles and see if it was useful to him.

Kojiro Sasaki's Rockstream Sword Style couldn't do that, and the Swallow Return Sword Technique could only teach a mortal version—it definitely couldn't achieve the effect of the Noble Phantasm Dimensional Slash.

So when Dan Lei saw Sakonji Urokodaki looking confused, he quickly explained.

"Mr. Sakonji Urokodaki, it seems you might have misunderstood. I want to learn Breathing Technique because I'm curious about the skill that lets ordinary people unleash elemental attacks.

To be honest, my methods may seem miraculous, but they demand extremely high talent.

Not to brag, but out of a hundred million people, not one would have the same level of elemental affinity talent as me.

So, being able to let ordinary people with low elemental affinity use elements—if I can research the principles behind it, the value would be enormous."

When Dan Lei put it that way, Sakonji Urokodaki found it acceptable, and he even felt more at ease with Dan Lei.

After all, someone who could humbly learn from lower-level abilities and wanted to absorb their strengths was a modest person, and such people were rarely truly evil.

But Sakonji Urokodaki didn't agree on the spot. He said that Breathing Technique was the property of the Demon Slayer Corps, and teaching it to an outsider required approval from above.

Dan Lei knew that Breathing Technique wasn't really considered the Corps' property—as long as it was used to slay demons and not for evil, a trainer teaching it to someone outside the Corps wouldn't cause major issues.

Fortunately, as a Longevity Species now, Dan Lei had plenty of patience, and from what he knew of the Demon Slayer Corps, they'd likely agree, since they supported anything beneficial to killing demons. So he replied.

"Reasonable. I am a sudden outsider, after all, and you don't know much about my background.

But please, in your letter, convey my greetings to your organization's leader.

Also, tell your leader that cooperation starts with contact. You can consider this a pilot project for cooperation between me and the Demon Slayer Corps. My investigation into demons won't be finished in a year or two—time will prove everything."

Seeing Dan Lei so reasonable, Sakonji Urokodaki's goodwill toward him shot up, and he said he'd make sure to clearly outline the stakes in his letter.

Sakonji Urokodaki didn't want to sour things with Dan Lei at all. After all, the man had a super-strong expert by his side. If Kojiro Sasaki really was a bodyguard, then with a guard of that level, Dan Lei's status was unimaginably high.

Just as Dan Lei had expected, his request to learn Breathing Technique passed through the Demon Slayer Corps with unusual smoothness. Tanjiro's injuries from tumbling down the mountain through traps hadn't even healed yet when the letter of approval for cooperation arrived.

And the letter explicitly stated that if Dan Lei wanted, he could find instructors for all five major Breathing styles.

But Dan Lei wasn't the type to have his eyes on the pot while eating from the bowl. The Sustainer Dragon Clan was best at controlling water, so Dan Lei decided to learn Water Breathing first, figure out its principles, and then consider whether to learn other styles.

So Dan Lei showed off a little again, healing Tanjiro—who was covered in wounds and would've needed several more days of rest—in just a few minutes.

The healing ability of the Abundance Destiny looked to Sakonji Urokodaki like it could bring the dead back to life and regrow flesh from bone. A wound as long as a hand, barely scabbed over, healed completely in seconds.

Of course, Dan Lei knew that the Abundance Destiny's power was essentially the conversion of life force. The Power of the Path could amplify and more efficiently convert life force, allowing rapid recovery from injuries, and it could heal any wound.

That said, the Imaginary Energy of the Abundance Destiny could also substitute for life force consumption, but that wasn't something a Pathstrider of Dan Lei's level could do.

As the caster, if Dan Lei didn't use his own life force or medicine, the healing consumed the patient's own life force.

Minor injuries were no big deal—a good meal or extra sleep would replenish it. But for major wounds, if done this way, the healed person would end up looking like they'd starved for days.

That's why the longevity granted by the Pharmacists of Abundance was a crooked path. Once life exceeded the blessing's limit, you had to plunder other lives to sustain yourself, or else face the Five Decays of the Celestial.

Of course, blessings had grades. The Celestials of the Xianzhou were the highest tier, the envy of all the Antimatter Legion, because the Xianzhou people's lives seemed truly infinite—they couldn't reach the blessing's limit even after millennia. What was called the Mara-struck state seemed more like a transformation of life to other Longevity Species, not death.

Anyway, after being revived on the spot by Dan Lei, Tanjiro ate a huge meal and could start training that very day.

So Dan Lei began receiving instruction alongside Tanjiro.

But while Tanjiro needed to keep building his foundation, Dan Lei jumped straight into learning Breathing Technique.

Let's just say the Sustainer Dragon Clan's body was too strong. Dan Lei learned Breathing Technique almost instantly—in less than a week, he could already swing out water currents through breath control alone.

At this point, Dan Lei confirmed the truth of Breathing Technique: it was a mana refining method that didn't require Magic Circuits.

Yes, no matter how you looked at it, the elements unleashed by Breathing Technique still needed mana, or rather, a special kind of mana called True Qi.

Unlike mages who absorbed mana from the external Great Source through Magic Circuits, Breathing Technique obtained mana from the air inhaled.

Those who trained in Breathing Technique developed lung capacity far beyond ordinary people, allowing them to inhale a massive amount of air in one breath.

The air naturally contained mana particles. Those who mastered Breathing Technique could refine these particles in their respiratory tract and lungs, forming a special gaseous mana that flowed directly through the body's meridians—different from Magic Circuits—much like the True Qi in martial arts novels.

This was what the anime meant by enhancing blood flow and delivering energy to every cell to boost their vitality.

Honestly, before practicing Breathing Technique, Dan Lei had never sensed that there were specialized energy-circulating meridians within his blood vessels. Even the Xianzhou's medical knowledge didn't mention them.

But when Breathing Technique was refined to the point of [Total Concentration], the meridians for circulating energy within the blood vessels revealed themselves—they were located slightly deeper than Magic Circuits, but the two didn't conflict at all.

However, Breathing Technique clearly didn't have the concept of cycling energy through the body's circuits. The energy converted from inhalation in the meridians was used up once spent, and even if unused, it would naturally dissipate into the body.

Still, this could passively strengthen the body to some extent. So mastering [Total Concentration Constant] and being able to freely unleash elemental attacks was a necessary condition for becoming a Hashira.