"Hisoka's match? Of course I'm going to watch."
While supervising Kurapika's training in our room, Gon and Killua dropped by. It seemed they had come to invite us to spectate Hisoka's upcoming bout.
"Watching Hisoka fight should serve as excellent training in itself, after all."
"Naturally, I will attend as well. Or rather, in my case, it's practically mandatory participation."
Indeed. More than for me, it was for Kurapika's growth. Observing higher-level combat firsthand is an invaluable study in itself.
"Alright, let's head out now. Even with priority passes, getting through the crowds is gonna take a while."
"Hisoka's matches seem insanely popular. I heard scalpers are out in full force."
"Morbid curiosity, most likely. Many people are drawn to gruesome spectacles."
"Most of his opponents probably ended up dead, right?"
"Spot on, Aisha. Out of eleven matches, he has eight wins, three losses, and six KOs—and the KO count is literally the body count."
Just as I thought. Honestly, I can't fathom what is enjoyable about murder. One could easily win without taking lives; this is why thrill-killer psychopaths are so insufferable. The Zoldycks are practically decent by comparison since they only kill for business. ...Though to the victims, a killer is a killer regardless.
"Is it really alright, though? Killua aside, shouldn't Gon avoid watching? You have that promise with Wing-san, don't you?"
"Uuu... yeah, that's true. Is even watching matches off-limits, I wonder?"
"It should be fine, right? It's not training, just sitting in the audience."
"No, Killua. Spectating a high-level Nen match is undeniably a form of study and training."
Besides, Wing-san has been listening to this entire conversation from behind that pillar... Ah, speak of the devil, here he comes.
"It is forbidden."
The boys jumped in surprise. Truly a certified assistant master—his Zetsu and presence concealment are top-notch. ...Though wait, doesn't Wing-san look completely drained? His cheeks are sunken and he looks utterly hollowed out!
"Watching Nen matches constitutes analyzing and studying Nen. Gon-kun, you must dedicate the remaining month solely to medical recovery."
"Yes, I understand... But Wing-san, why do you look so gaunt?"
"Yeah, your complexion is awful! You look completely pale!"
"If you are feeling unwell, I strongly advise taking proper rest."
"You don't strike me as someone negligent with personal health, but did you catch a severe cold?"
His condition was visibly dreadful, and his aura was noticeably faint. A shell of his usual self!
"...Listen well, everyone. Never casually promise someone that you will 'do anything.' Take this as advice from an elder in life."
"A-Ah... (He was drained completely)."
"Understood... (He was thoroughly milked)."
"I will etch it into my heart... (He was completely squeezed dry)."
"Got it! (Man, I wanna get back to Nen training soon!)"
Shion... I know you won't see him for a while, but this was overkill. That was clearly an all-night marathon, no doubt about it.
...I wonder where poor Zushi-kun ended up staying?
"By the way, I'm shocked you promised to marry Shion-san. Isn't that moving way too fast?"
"Killua-kun... No, let me say this to Gon-kun and Kurapika-kun as well. ...There are moments in a man's life when he must take full responsibility."
Exuding a heavy aura of masculine sorrow, Wing-san turned and trudged away... While partially self-inflicted, it felt a little too harsh.
"...Well, leaving Wing-san aside, Gon, record the broadcast for yourself. You can watch it later."
"Indeed. For now, only the three of us will go. My apologies, Gon, but these tickets were not cheap."
"Sorry, Gon."
"It's fine! I'll practice Ten while waiting for you guys!"
Regrettably, Gon had to stay behind in his room. Having broken his promise, it couldn't be helped.
"So, about Hisoka's opponent—he's supposedly the only fighter here who has ever scored a knockdown against Hisoka."
"Ah, his name was Kastro, correct? To score a down against Hisoka, he must be remarkably skilled."
"Apparently that occurred roughly two years ago. He likely awakened to Nen during that encounter."
"A fated grudge match, huh. Who do you think will take it?"
Hmm. Having never laid eyes on this Kastro person, I couldn't be entirely certain, but...
"Nine times out of ten, Hisoka."
"Whoa, that was definitive. What's your reasoning?"
"Kastro has only known Nen for two years, and having awakened without prior knowledge, he likely has no master. Nen is not so shallow that it can be mastered in isolation."
Nen is like a vast academic discipline. Modern Nen was built upon centuries of accumulated insight. Trying to self-teach from scratch severely limits how far one can reach.
"Even if Kastro is a prodigy, reaching Hisoka's realm in just two years is virtually impossible without a mentor."
Most Nen users here share Kastro's plight. They reach the 200th floor ignorant of Nen, receive the 'baptism,' and if lucky, survive without permanent maiming. But even without disability, lacking proper guidance leaves them clueless about systematic training.
Watching Gon's previous recorded matches, his opponents were pitiful. They couldn't knead proper aura and relied on abilities incompatible with their natural affinities. You cannot become a legitimate Nen user that way.
"In short, Kastro's odds of defeating Hisoka are practically non-existent."
"I see... We were fortunate to have proper teachers from the start, then."
"Indeed. Our starting line was properly established."
"Encountering a master depends heavily on environment and luck. True Nen users are remarkably rare in this world."
Had I not met Master Ryuzen in my previous life, who knows where I would have ended up? If I had continued bumbling through self-taught training, I definitely wouldn't be here today—I'd have perished in some ditch.
"There's still an hour before the match, but the arena is already packed."
"Yeah, without priority tickets, we wouldn't have gotten seats."
"Look, you two! They're selling popcorn and juice over there! Let's grab some!"
"Did you come here to watch a baseball or soccer game?"
"I will pass. I wish to maintain total concentration on this battle."
Ehhh~ Nibbling on snacks makes spectating so much more enjoyable!
Well, those two should probably focus on observing. I'll just buy some for myself.
The Duel Commences
"And nooow, the moment you've all been waiting for!! The epic clash between Hisoka and Kastro begins!!"
Here it comes.
So that is Kastro... I see. He has good reason to be confident in challenging Hisoka. I honestly underestimated him, assuming anyone who awakened to Nen in this arena would be mediocre.
"You two... munch, munch... I take back... nom, nom... what I said. That man is... chew, chew... far stronger than I anticipated."
"Either talk or eat, pick one!"
"Your manners, Aisha."
"My apologies... It's been so long since I had popcorn, I couldn't resist..."
A moment of self-reflection. Munch.
"So, is he actually strong?"
"Yes. You can tell simply by observing his Ten. A refined, robust aura shrouds his body without a single ripple of waste. Facing Hisoka, he shows slight excitement, but it's creating an optimal combat mindset."
Despite having lost to Hisoka once before, he shows no excessive tension. That proves he practices Ten relentlessly. Did he genuinely achieve this level through self-study? Or did he find a mentor?
"I cannot judge fully without seeing his Nen techniques, but at the very least, he has not grown complacent or neglected his training."
"...Meaning he might put up a far better fight than expected."
"Whoa, could he actually beat Hisoka?!"
No, Hisoka still holds the upper hand... but since neither has revealed their full hand, I cannot say for sure. Depending on his Hatsu, an upset isn't completely impossible.
...And those gloves.
He wears a standard martial arts gi—sleeveless for mobility—yet wears leather gloves extending nearly to his elbows. Is it a weapon? Are weapons concealed inside? Thin leather gloves wouldn't hinder finger dexterity much... What is his objective with those?
"I thank you, Hisoka. It was your baptism that granted me the catalyst to become strong."
"...Kukuku♣ How delightful... I understand completely how a connoisseur feels when uncororking a finely aged vintage♥"
Hisoka feels it too—Kastro's authentic strength...
Hisoka likely spared Kastro during his baptism on purpose, recognizing his potential and deciding it was a waste to crush him as an unripened fruit.
And now, meeting again after two years, the prey stands before him vastly upgraded. Hisoka's heart must be surging with twisted ecstasy. Though he keeps it contained, his repulsive aura is steadily swelling.
"I will not claim to have perfected Nen, but I have forged fangs capable of reaching your throat... Here I come!"
With the referee's starting signal, Kastro unleashed Ren. ...What immense output! Truly staggering for someone with only two years of Nen experience!
He sprinted toward Hisoka, gathering aura in his feet to generate explosive acceleration, launching into a rapid flurry: right, left, feint left, into a right roundhouse kick!
Kastro is clearly a strike-oriented martial artist, utilizing open-palm and knife-hand strikes rather than closed fists. Judging from his hand formations, is he a practitioner of the Tiger Bite Fist (Kokou-ken)?
His physical martial arts are exceptional. Furthermore... his aura mechanics are finely polished!
Every single strike is backed by Ryu (aura flow). Seamlessly shifting offensive and defensive distribution at high combat velocity! Hisoka remains in pure defense to gauge his opponent, but Kastro doesn't slacken for a second, constantly flashing Gyo to the eyes to counter any hidden tricks Hisoka might deploy!
Hm? Kastro is shifting to a deeper offensive.
Feints... four of them! One with eye movement, three with body posture... No, an aura feint as well!
—!
Clean hit!!
Hisoka took a direct blow! His Gyo guard was too slow! While Kastro's striking aura was light, the damage definitely registered!
"Show your true strength, Hisoka! As a martial artist, I wish to settle this against you at your full power!"
"First blood goes to Kastro!! Dodging through a dazzling sequence of feints, he scores a clean strike against Hisoka!!"
"Hey! Why did Hisoka take that hit?! Even I could tell Kastro was swinging with his left!"
"Indeed. Several feints were layered in, but using the right as a decoy to strike with the left was clearly readable. It's hard to believe Hisoka failed to perceive it."
It's natural for Killua and Kurapika to be confused. That feint only works on advanced Nen practitioners.
"Yes, you are right. Kastro used a feint that only works against skilled Nen users who actively read aura."
It was an aura distribution feint.
High-level Nen combat relies on reading your opponent's Ryu. Where aura concentrates, the attack lands; where it thins, defense is weak. Reading flow is step one for masters.
Hisoka was reading Kastro's Ryu. Kastro made a body motion suggesting a left strike, but heavily pooled his aura into his right fist. Seeing that, Hisoka braced to defend the right—whereupon Kastro struck with his lightly-infused left fist instead.
Hisoka underestimated Kastro, thinking a two-year novice wouldn't utilize psychological Ryu deception. Combined with Kastro's previous strikes all being heavily reinforced with Gyo, the sudden shift caught Hisoka completely off guard.
"—And that is how it played out. Though because his left fist had minimal aura, the actual damage was negligible."
"..."
They were speechless. Aura flow mechanics were still beyond their current curriculum.
"Ku... kukuku♥ I see, you truly are different from two years ago♠"
"Precisely. ...Are you ready to fight seriously now?"
"Yes, I'm getting quite motivated. ...To think you'd ripen this beautifully♦ I must extend my gratitude to your master♣"
Indeed. At this stage, it was unthinkable that Kastro had no master. Achieving this level entirely self-taught in two years was statistically impossible.
"Gratitude, you say...? Unfortunately, I have no master."
WHAT?! Impossible! Truly self-taught to this degree?!
"I-I cannot believe it... What monstrous talent must one possess..."
"Aisha..."
"Hey, is Hisoka actually in danger of losing this?!"
I don't know... If Hisoka fights seriously, his baseline prowess is still superior. But with a prodigy of this caliber, there is no telling what unpredictable Hatsu he might wield.
"No master... If that is true, you are quite something♥"
"I have no reason to lie. ...Though there is one whom I revere as my master in spirit."
Eh? What does that mean? He doesn't have a master, but has a master in spirit?
"...What do you mean by that?"
"Heh... very well, I shall enlighten you. The reason I, who was once defeated by you, was able to ascend to this height."
"Whoaaaa! Fighter Kastro begins sharing his backstory mid-match!! What an unprecedented scene!!"
Seriously, what is with this monologue? But I can't deny my curiosity. Let's listen closely.
"After receiving your baptism and awakening to Nen, I sought information regarding this power."
"Wait, isn't Hisoka just recovering his stamina while he talks?"
"He's probably fully recovered already."
"Well, let him speak. He seems eager to share his journey."
Perhaps he simply wanted someone to acknowledge his grueling efforts.
"I learned the name 'Nen' from fellow 200th-floor fighters, but none would teach me the training methods. I investigated on my own, but found nothing... Just as I resigned myself to blind trial and error, I stumbled upon a miraculous relic."
Slurp.
"Circulating on the black market was a tome priced so exorbitantly it seemed absurd for a single book. Yet upon reading its description, I purchased it like a drowning man clutching at a straw. Fortunately, I had accumulated substantial prize money here, so I managed the funds."
Wait. Why am I getting this overwhelmingly dreadful premonition? The sudden spike in anxiety is making my throat bone-dry. Let me take a sip of juice.
"That legendary text was none other than the definitive Nen manual authored by the mythical martial arts grandmaster, Ryusho Kazama—The Black Book!"
PFFFFFFTTTTTTTTTTTTTTTTTTTTT—!!!!!
"WHOA, WHAT WAS THAT?!""WHO SPIT ON ME?!""WAIT, IS THAT A BEAUTIFUL GIRL?!""NEVER MIND, NO PROBLEM!""IN FACT, IT'S A REWARD!""AISHA-TAN, LICK LICK!"
Cough, cough, wheeze!
"A-Aisha, are you alright?!"
"Hey, who were the creeps in the back row?! Step forward, I won't get mad, I'll just kill you."
I choked so violently I sprayed juice everywhere! I feel terrible for the spectators in front of me, but right now, my mind is completely shattered!
The Black Book?! Did he just say The Black Book?!
"Within The Black Book, countless Nen abilities and rigorous training regimens were documented in meticulous detail! I followed its instructions to the letter and trained my Nen!"
HE REALLY SAID THE BLACK BOOK!!
H-Hahahahaha... HAHAHAHAHAHA! F-O-U-N-D Y-O-U!
IT WAS YOU, KASTRO...?! YOU WERE THE ONE WHO BOUGHT MY CHUUNIBYOU NOTEBOOK, BLACK HISTORY?!
"If I must name a master, it is the late Grandmaster Ryusho. ...How I wish I could have met him in life."
I NEVER ACCEPTED A DISCIPLE LIKE YOU!
...Well, being revered so passionately isn't the worst feeling in the world.
Still, everything makes sense now. In Black History, I transcribed all the Nen principles recalled through Original Knowledge, and later refined the gaps using Master Ryuzen's genuine training methods. Following those instructions with relentless diligence would indeed produce this level of mastery!
...Though his innate talent is still undeniably monstrous.
No, this is no time for admiration! I must reclaim Black History at all costs! I need to incinerate that embarrassing relic from the face of the earth!
How do I get it back? Is it in his room? I can't go breaking into fighters' quarters...
Once the match ends, I will beg him to sell it to me! Even if it takes my entire savings! If that's not enough, I'll take out loans!
"U-U-UNBELIEVABLE!! The name of the legendary grandmaster, Ryusho Kazama, has been invoked!!"
DON'T SHOUT THAT NAME INTO THE MICROPHONE! You'll let the entire world know that Ryusho was a massive chuunibyou cringe-lord!!
"Ryusho Kazama was a mythical powerhouse who conquered Heavens Arena as a Floor Master before resigning! And fighter Kastro obtained his secret sacred text!!"
Stop giving commentary on my past life! That's not fan service, that's psychological torture!!
"Following those true training methods, I vomited blood in relentless discipline for two years. Nen is far from shallow, but I have forged the power to match you!"
"Fascinating♥ You truly have grown strong. ...You were worth keeping alive♦"
Hisoka's aura flared outward, darkening with thrilling malice. He had discarded all restraint, drunk on the thrill of prime prey.
"Is this... Hisoka's true power?!"
"Dammit, what a monstrous aura!"
...Wait, is my aura really that much worse than his? Mine doesn't carry bloodlust, but because it's naturally pitch-black, does it seem more terrifying? I really don't want anyone to see it.
"Come, Hisoka! This is the battle I yearned for!"
"Fufu, here I come. Don't break too easily♣"
"You two, open your eyes and observe with 'Gyo'!"
"Right!"
"...Focusing with 'Gyo', understood."
Kurapika caught the pun immediately. He can already use Gyo smoothly—what a prodigy.
The Climax
The battle escalated instantly.
Hisoka went on an aggressive offensive, unleashing relentless barrages of strikes. His movements were chaotic and freestyle, but every punch carried terrifying mass and pinpoint Ryu distribution.
Kastro defended masterfully. Unfazed by Hisoka's irregular rhythm, he blocked cleanly and looked for counter-openings.
Wait... what is that? A thin thread of aura extending between Hisoka and Kastro?
"What is that?!"
Kastro noticed it as well. A thread of aura connected Hisoka's right fist to Kastro's left forearm!
"Kukuku, by the time you notice, it's already too late. Hup♠"
"What?!"
Hisoka jerked his right arm back—and Kastro's left arm was forcibly yanked forward! Knocked off balance, Kastro took a direct strike flush to the jaw!
Critical hit & Down! 3 points to Hisoka! 3–1!
What is that ability?! Sticky, rubbery aura attached to Kastro, contracting and expanding at will? A Transmutation ability altering aura into a gum-like substance!
Attaching upon physical impact makes it a nightmare for close-quarters fighters. If touching him attaches the gum, you have to avoid every single trade!
"Kh! What is this aura?!"
"Fufu, now what will you do?"
Dammit! This aura attached to my arm stretches when I pull, but snaps shut when HE pulls, dragging me forward!
"Careful now! Guarding carelessly will cost you!"
Another thread attached to my right arm?! It attaches on physical contact?!
Gyo won't save me if he can apply it through ordinary strikes without In!
"Come over here♥"
"Out of my way!"
Kastro intercepted Hisoka's incoming kick with a counter-kick, neutralizing the blow and leaping backward!
"Oh, impressive defense♦"
"I told you—I am not the same man from two years ago!"
I must break these threads! Physical blunt force won't work—it merely stretches!
If blunt force fails... then I must use THAT! This is no time to hold back!
"Your ability is well-crafted, Hisoka. Few techniques are as frustrating to face."
"Thank you♣ But please don't forfeit just yet♥"
What a terrifying, sinister aura... Stand firm, Kastro! If you cower, victory slips away!
"Fear not. I have already devised the means to sever your technique."
"Oh? How delightful... show me."
"HAAAAAAAH!"
—!
Kastro crossed his arms and sliced through the sticky threads with burning black flames!
"Is that... black fire?!"
"Heh, finally, I see astonishment upon your face! This is the sacred art recorded in The Black Book, conceived by my revered master, Ryusho! Its name is... [Evil King Flame Fist / Jao Ensatsu-ken]!!"
"KYAAAAAAAAAAAAAAAHHHHHHHH—?!!"
"Aisha?!" "What happened?!"
Kastro heard a female cheer from the stands. Ah, she understands the sheer magnificence of this technique's name! Even my revered master Ryusho had exquisite naming sense!
"And by fusing [Jao Ensatsu-ken] with my Tiger Bite Fist, the ultimate art is born: [Jao Ensatsu Koko-ken / Evil King Flame-Slaying Tiger Bite Fist]!!"
"And fighter Kastro goes with the literal combination name—!!"
Quiet, referee! It sounds magnificent!
"NOOOOOOOOOOOO, STOP IT ALREADY—?!!"
"Calm down, Aisha!!""She's completely losing her mind!"
Listen to that passionate cheer! True connoisseurs recognize greatness!
JUST KILL ME NOW! Why am I being forced to witness my ancient, cringeworthy sins reenacted in broad daylight?! My face is burning with mortification!
"A-Are you alright, Aisha?"
"Y-Yes... I lost my composure for a second, but I'm fine now."
"A second? You were screaming like your soul was being ripped out."
Don't pry, Killua! I want to bury that memory six feet under!
To think Kastro actually mastered Jao Ensatsu-ken! Did he recreate it based on the nonsense notes I scribbled 100 years ago?! Wait, what vows did I even attach to that?! I don't remember a thing!
"Black flames... altering aura into fire..."
"Yes. Transmuting aura into elemental properties is far more difficult than simple shape manipulation. Turning aura into genuine flame takes absurd dedication."
"Does the black color have a specific purpose?"
"...Probably none whatsoever."
Flame temperature doesn't correlate to pitch-black aura in real physics. There was zero practical reason—it was 100% pure edge.
...Though having written it myself, I can't even remember why I made it black.
The clash resumed. With Hisoka's rubber threads severed, Kastro pressed forward with ferocious flame-infused tiger-claw strikes!
Because Kastro's fists were cloaked in scorching heat that distorted the surrounding air, Hisoka could no longer block or parry—touching the flames meant severe burns. Hisoka was forced entirely onto the defensive, evading with agile footwork.
"What's wrong, Hisoka?! Are you afraid?!"
Hisoka smiled with genuine delight, completely intoxicated by the challenge.
However, Hisoka subtly sent a hidden thread of Bungee Gum toward Kastro's foot using In.
"Fascinating... but not without weaknesses♥"
Snap!
Kastro's left foot was snagged, throwing him off balance. Though he instantly burned the thread, Hisoka's roundhouse kick caught him square in the ribs, sending him crashing into the floor!
Clean hit! 1 point to Hisoka! 4–1!
"You're focusing too much aura on your hands. That leaves the rest of your body vulnerable♠"
Hisoka's battle IQ is terrifying. He spotted the flaw instantly.
Maintaining Transmuted fire and reinforcing his protective leather gloves required at least 80% of Kastro's aura concentrated in his hands. His body defense dropped drastically, and he couldn't maintain Gyo in his eyes to spot In.
Furthermore, sustaining elemental Transmutation burns aura at a monstrous rate.
"Yet I am not finished!"
Kastro roared, feinting a desperate double-fist thrust—only to abruptly cancel the flames, shift Gyo to his leg, and land a crushing spinning kick straight to Hisoka's temple!
Critical hit & Down! 3 points to Kastro! 4–4!
"I know my technique's flaws! I have trained to compensate for them!"
Hisoka staggered up, his aura expanding to twice its previous magnitude, snuffing out the flames on his singed clothing.
"Splendid, Kastro♥ But you lack real-life combat experience♣"
Hisoka vanished in a blur of speed, piercing Kastro's guard with a brutal gut punch, followed by rapid combinations that battered Kastro across the ring!
Critical hit & Down! 3 points to Hisoka! 7–4!
"Haa... haa... Impressive, Hisoka... I may still be inferior to you in close combat... BUT!"
Kastro gathered his remaining aura into his cupped hands, condensing it into a massive swirling sphere of black flame!
Wait... HE LEARNED THAT TOO?!
"VICTORY IS MINE!! TASTE THIS! [Jao Ensatsu Koko-ho / Evil King Flame-Slaying Tiger Roar Cannon]!!"
"STOP IT ALREADY, MY SANITY IS BREAKING!!"
A colossal tiger composed of blazing black fire erupted from Kastro's palms, roaring as it surged across the arena straight toward Hisoka!
Hisoka dodged the initial jaws, but the flame tiger twisted mid-air under Kastro's manipulation, clawing across Hisoka's cheek!
Yet as Kastro retreated to buy time for the tiger to loop back around, his feet stuck to the arena floor—Hisoka had laid a trap of Bungee Gum across the tiles beforehand!
"Guh?!"
Hisoka closed the distance, launched Kastro into the air with an uppercut, yanked him down with Bungee Gum, and drove a downward hammer fist into his chest, slamming him unconscious onto the ring.
TKO! Winner: Hisoka! (10–4)
"That was wonderful. I'll let you live for now♥ Gain more experience, and next time... we shall fight without rules♣"
Aftermath
"What an incredible battle..."
"Hisoka is terrifying."
"Even Kastro was far beyond us..."
"Do not fret," I assured Killua and Kurapika. "Your potential is equal to theirs. Focus on your fundamentals, and you will reach their level in time."
Leaving the boys to return to Gon, I snuck off to the infirmary to track down Kastro.
I knocked on his private recovery room door.
"Excuse me, Kastro-san? May I speak with you?"
"Come in... Ah, you are Aisha-san. What brings a fellow 200th-floor fighter here?"
"I'll be blunt. Will you please sell The Black Book to me?! Name your price—I will pay billions if necessary!!"
I bowed deeply in desperate supplication.
"Please raise your head, Aisha-san. ...I would gladly give The Black Book to someone who cheered so passionately for my techniques. But..."
"B-But...?"
"I no longer possess The Black Book."
My vision spun.
"Two months ago, while training in a secluded wilderness, I fell deathly ill from eating wild mushrooms. A kind young rookie Pro Hunter happened upon me and nursed me back to health. To repay his life-saving kindness, and seeing that he had never learned Nen, I gifted The Black Book to him as a token of gratitude."
...
God is dead.
◆
[AN]
Here comes the newly overhauled character: Kastro! As a result of this extreme overhaul, Hisoka ended up taking an even greater liking to him, lol. Here are the details of Kastro's Nen abilities:
[Evil King Flame-Slaying Fist]
Type: Transmutation
Description: Transmutes aura into black flames. Transmuting aura into fire requires extraordinary effort, but Kastro's talent and passion (chuunibyou) made it possible. There is no practical reason for making the fire black—simply put, because it looks cool. While it seems like a waste of memory, Kastro's strong personal conviction is poured into it, resulting in increased power. Because the flames burn his own body (including his hands), the user will suffer severe burns unless wearing non-flammable gloves made of special materials and wrapped with ultra-thin heat-resistant taping.
＜Restrictions＞
Aura cannot be transmuted into flames anywhere other than around the hands.
These flames inflict thermal damage on the user's own body as well.
＜Vow＞
None in particular.