To understand the scene Muzan was witnessing, we need to rewind a few minutes.
At that moment, Kokushibō had just unleashed his Moon Breathing against Dōma. The ice demon found himself facing a veritable sea of crescent-shaped blades.
'Dodge? Impossible… Kokushibō is faster than me.'
From their first exchanges, Dōma had realized: his physical abilities were inferior.
After all, the longer a demon lives, the greater their power grows. This harsh truth worked against him. But Dōma wasn't the type to make excuses.
With a single thought, he summoned the four Miko he had conjured earlier.
In one fluid motion, they unleashed "Blood Demon Art – Frozen Lotus Petals."
A move that was both offensive and restrictive, yet far from a defensive specialty.
A strange choice… but Dōma had no other option.
He was convinced: any attack or parry would simply be sliced apart by Kokushibō.
It was as if Kokushibō's blade was a still sword placed upright in a river by a blacksmith. Anyone who approached was doomed to be cut, with no chance to negotiate.
So, rather than wasting his energy, Dōma chose to channel his supernatural reaction speed and attempt to hinder his opponent's breathing techniques.
He was essentially betting on dulling the blade that sought to cut through everything in its path.
"You plan to cut me down, Kokushibō-sama? But can you really damage what's already broken~?"Dōma's voice rang out, laced with mockery.
Kokushibō didn't immediately grasp the meaning of those words but charged forward, blade in hand, determined to engage in close combat.
A logical choice against a tactician and ranged fighter like Dōma.
Kokushibō's crescent moons were instantly swallowed by a cloud of icy dust, mixed with lotus petals conjured by the Miko.
Seeing this, he finally understood Dōma's words.
His katana couldn't truly defeat the lotus petals. Even when shattered, they reformed: either into ice crystals, making the air even more biting, or into thousands of tiny petals capable of hindering his every movement.
Kokushibō felt their restrictive effect on his Total Concentration Moon Breathing.
But as Upper Moon One, he could afford to ignore them. His superhuman regeneration compensated for the sting of the ice in his body.
However, the sudden drop in temperature posed a real problem: a chilling stiffness was relentlessly seeping into his body.
Sooner or later, Kokushibō would slow down.
"Blood Demon Art – Moon Breathing, Third Form: Loathsome Moon – Chains!"
Ignoring the constant pain inflicted by the icy dust, Kokushibō closed the distance in a single leap and executed two massive crescent-shaped slashes.
From these arcs erupted a storm of smaller blades, bursting forth like a rain of slicing moons.
Dōma frowned at the sight: his opponent was relentless, giving him no respite.
It was clear that Kokushibō distrusted his intelligence and had decided to neutralize him quickly.
"Miko!"Dōma shouted, his tone slightly urgent, devoid of his usual nonchalance.
He raised his two fans with perfect timing, ready to unleash a… "theoretical" attack.
Retreating was out of the question against Kokushibō's overwhelming pressure, as Dōma had quickly assessed.
Even if he managed to pull back, Kokushibō would close the gap in an instant, launching a devastating wide-range attack.
Dōma's only chance at that moment was to step into the eye of the storm.
He accepted Kokushibō's invitation to close-quarters combat, despite the obvious disadvantage.
Regardless, his initial goal remained unchanged: to perfect his Tessen-jutsu skills and address his weakness in close combat.
To overcome his lack of experience against sword-wielding, martial fighters.
"Just like I had to bet on his last attack, I have to bet on myself again…"he thought.
Dōma could only rely on his talent and current strengths.
He still lacked the necessary training, and his experience with his weapons was limited.
The Blood Demon Art – Paradise of Vanity soon found the most optimal solution to Kokushibō's aggression.
This demonic art allowed Dōma not only to read memories and emotions but also to alter them.
He even used it to modify his own perception, though this application was limited.
To put it simply, it was as if Aizen used his shikai to slow his own perception of the world, allowing him to analyze the situation more clearly.
Unfortunately, such a process had its limits.
Dōma himself.
If he was too weak, he wouldn't be able to react in time.
This sub-ability of the Blood Demon Art – Paradise of Vanity had a name: *Accelerated Thought.
An imitation of an extra skill from the world of Tensura.
That's how Kokushibō had managed to break his hand, despite Dōma's extraordinary reaction speed.
That's how Dōma could assess the best course of action by observing Kokushibō's ferocious offensive.
He decided the best strategy was to combine Kamiya's Flame Breathing with his vector manipulation, controlling the flow of information through *Paradise of Vanity*.
Against Upper Moon One's assault, the ice demon realized these three elements had escaped Kokushibō's notice.
Kokushibō was unaware of the vector manipulation and didn't know Dōma had stolen knowledge of breathing styles from a demon slayer.
Above all, Paradise of Vanity was currently Dōma's most precious secret.
Kokushibō could never have imagined how terrifying Dōma's mind could be.
"F… Flame Breathing Technique, Fourth Form: Blooming Flame Undulation!"
'Blood Demon Art: Vector Manipulation!'
The image of Kamiya spinning to defend against Dōma's icy lotus petals flashed in his mind, and Dōma replicated the movement perfectly.
The only difference lay in the weapon used and the way the technique was applied.
Dōma seemed to dance under the onslaught of Kokushibō's crescent moon blades, while Kamiya had appeared far more disciplined against Dōma's icy petals.
This feat was made possible by biological manipulation and the stolen memories of Kamiya: every sensation of the technique's perfect execution already resonated in his body.
Until now, Dōma had lacked a true sparring partner.
Now, Kokushibō stood before him.
"W… What!? A breathing technique!?"
Kokushibō's six eyes widened in shock, but he quickly regained his composure.
He had already killed countless demon slayers, including Flame Hashira.
So, he wasn't intimidated by this unexpected move and noted it as another factor to consider.
Dōma spun his fans, using vector manipulation to deflect the relentless assault, then hid behind a curtain of ice crystals projected by his Miko.
"You… hiding?"
Kokushibō didn't have time to finish his sentence: Dōma had already closed the distance, unleashing the second form of Flame Breathing, aiming straight for his neck.
"Ho ho~… Kokushibō-sama, you were keeping such a nice trick to yourself?" he taunted, referring to the breathing technique.
Due to the brutal clash between their "two" weapons, sparks flew from the friction between "one" of Dōma's fans and the opposing katana.
But there were clearly cracks in Kokushibō's blade, caused by the vector manipulation that continually redirected the force applied to his own blade.
It was only a matter of time before Dōma's fans would pierce his throat.
"Don't… get cocky!"
Suddenly, multiple blades sprouted from Kokushibō's katana and body.
Unfortunately, Dōma's attention was focused on the Miko in the rear, due to a large-scale ice attack.
He was even using his vector manipulation offensively, as Kokushibō physically outmatched him.
This led to the current moment.
For the first time since his reincarnation… Dōma truly bled—not just a faint red line like with Kamiya, but real blood.
As if the universe had decided to raise the stakes, an overwhelming presence filled the room.
Muzan had arrived.
If Dōma didn't retreat immediately, this simple sparring match risked turning into a true duel under the eyes of the demon progenitor.
"Cough… K-Kokushibō-sama… Y-you're really a tough one, aren't you?"he said, stepping back slightly.
But he didn't leave the range of Kokushibō's blade.
Dōma flashed a "sincere" smile before picking up Kokushibō's arm, which had fallen to the ground moments after their standoff.
"*Chomp*… you know what? It'd be a shame if this training match turned into a fight to the death… don't you agree?" he said, after devouring Kokushibō's arm.
For the first time in his two lives, Dōma exuded genuine fighting intent.
He wanted to see how far this battle would push him to evolve and innovate on the spot.
'Too bad Muzan's here… I wanted to see how far I could influence Kokushibō's emotions, memory, and perception.'
The Blood Demon Art: Paradise of Vanity had met all the conditions to work on Kokushibō.
If the Upper Moon refused Dōma's offer, the battle would escalate to a point where the outcome would be uncertain.
Something Dōma, a rational man, did not desire.
****
Author's Note:
I just want to clarify that the Flame Breathing technique won't be the one Dōma uses in the future. In this fight he simply had no choice—Kokushibō gave him neither the time to unleash a wide-range attack nor to summon his giant Buddha… which, by the way, he hasn't yet mastered or devised a perfect plan to wield.
Remember that Mitsuri's Breathing Style is a derivative of Flame Breathing. That's why Dōma was able to handle the explosive, aggressive nature of the technique, even though it's not really his fighting style.
It's also important to understand that Dōma would already be dead if he were human—Kokushibō literally impaled him.
However, Dōma considers the battle undecided: Kokushibō hasn't shown his full strength, and Dōma can now read his thoughts to some extent. By consuming a tiny fragment of him, Dōma can partially alter his emotions, memories, and even his thoughts.
Additional info: I released a bonus at 650 stones (that's 100 more than when I first wrote this).
Another bonus will unlock if you reach 800 stones (150 more).
I'm counting on you! ~
Chapter word count: 1,400+
(Note: My chapters are at least 1,200 words, and when inspiration strikes they can reach 1,900–2,000 words.)