It breathes. It pulses.
As if the bamboo grove were a single living creature.
＊
The first thing Kokushibo received upon setting foot in the bamboo grove chasing the fleeing boy was a baptism of bamboo spears. He deflected with his arm the slender bamboo spears, sharply cut diagonally, that flew through the air, something that was impossible to believe was prepared in the short time it took him to enter the grove.
Then this time, the sound of wind groaning from the side. Sensing the anomaly and stepping back, a bamboo whip lashed down where he had been standing just a moment before. Immediately after, as if predicting where he would retreat, bamboo flew like arrows toward that spot as well.
Barely evaded. A red line was drawn on his cheek grazed by the bamboo. Such a wound on a demon's body means nothing. Yet Kokushibo shuddered. He was astonished that a boy had wounded him with mere bamboo. He couldn't believe these relentless attacks were being carried out by a single child's hands.
The attacks don't wait for a stunned Kokushibo.
In the Warring States period, the Myouju had once been covered in bamboo leaves and crawled out of a bamboo grove. Even Suuju had his spirit broken and stumbled out fleeing. Both were masters counted among the Demon Slayer Corps and Demon Slayer Mark bearers. The first time he saw that, he had looked down on them thinking 'to be beaten by a single child, how weak,' but that wasn't it.
Only now, as Kokushibo, did he realize Tsugikuni Michikatsu had been mistaken. Those two were truly strong. What he had truly looked down on was──Young Moon.
Countless bamboo attacking from all directions as if sucked toward Kokushibo, leaving no room for carelessness. They were like the claws of a beast with will. An attack impossible to believe came from a single human.
Is this really a bamboo grove?
Did I jump into a monster's maw?
The utterly featureless bamboo grove was breathing, having gained a heart called 'boy'.
Like spears, like whips, like arrows, the blue weapons targeting Kokushibo. Now he understood the Myouju's state of being covered in bamboo leaves. He could sympathize with Suuju whose spirit was broken. This is something that can't be helped even if it happens. Kokushibo, whose back was grazed by bamboo from a delayed evasion, understood.
If even a demon's body couldn't evade perfectly, a human receiving this bamboo onslaught would certainly be helpless. If you're a demon, wounds heal in an instant, but humans are not like that. Enduring the accumulating pain and fatigue to break through the bamboo grove would be a grueling task for a human body.
But with a demon's body, pushing through is possible.
Especially Kokushibo is Upper Moon One. His toughness, agility, and recovery are on a different dimension from ordinary demons. Because he is considered the strongest demon after Kibutsuji Muzan. It's not a problem even if he can't read the attacks and takes bamboo strikes. He could even advance while taking attacks. Using Moon Breathing, whose slashes reach widely, sweeping away the bamboo grove would be an easy task.
But he doesn't.
Because it's not beautiful. It's too rude. It's discourteous as that child's teacher.
Above all, Kokushibo, who abandoned his human body long ago, was feeling excited for the first time in ages.
Sharpening his five senses, opening the perceivable world to distinguish the sound of cutting wind, jumping to avoid the bamboo attacking from the blind spot behind. And the bamboo spears fired as if chasing where he jumped.
Surprisingly, these spears aren't newly made each time they attack Kokushibo. That they're reusing the few bamboo spears thrown at first could be known from the fact that those spears that should have been stuck in the ground had disappeared. Yes. The boy wasn't staying in one place but was traversing the bamboo grove纵横无尽, avoiding Kokushibo's eyes.
In his airborne posture where he couldn't move, Kokushibo could have flashed his sword to cut down the approaching bamboo. But he deliberately didn't, twisting his body to focus on evasion. He held back.
He didn't want to cut down his disciple's efforts to resist with limited weapons. That child doesn't even have a Nichirin Sword. Drawing it against a human who can't even wield a sword blade would disgrace a warrior's honor.
Bamboo attacks Kokushibo again as he lands. Not even a moment to catch his breath!
Looking at the perceivable world, he could easily tell where in the bamboo grove that child was. Yet even if he could capture them with his gaze, he realized it wouldn't be easy to seize them with these hands.
The figure of the child running violently through the bamboo grove more than Kokushibo focused on evasion. The heart pounds, lungs swell, muscles are overworked—the boy was using his young body without reservation, to the point where aftereffects would likely remain later. That spirit to flee until dawn even beyond the limits of his own stamina. That determination to escape from Kokushibo to that extent.
Splendid, splendid, splendid!
Yes, this tenacity!
This tenacious determination is what I liked!
Kokushibo doesn't know why his master Kibutsuji Muzan is looking for a white-haired, red-eyed child. Within those conditions, he can't know what that person uses to judge the correct answer.
But if this child is the wrong answer and an unnecessary existence to him, then at that time, I want to give him this blood and make him a demon. If I teach you all the forms I devised after your death and we undergo endless training together, you too will soon reach Upper Moon.
Come here. Come to me.
When you return to my side, the moon's (my) wish will finally be fulfilled.
Dreaming of that night, Kokushibo smiled as if his six eyes would melt.
However.
"Uwaaaaah it's twice as scary when you smiiiiiile!! Could you stop glancing over here since earlier?! How do you know where I am that's amazing?! Are those eyeballs equipped with night vision or something how high-spec are they what's your vision are you Mongolian you bastard!! Go home and drink some mare's milk and sleep quickly nomads wake up early in the morning it'll affect tomorrow damn it!! Get astigmatism, farsightedness, nearsightedness in those eyes from the top down or just get strabismus!!"
I don't have glasses to give you!!
The boy shouted from within the darkness.
It stabbed deeply into his heart. A demon's body is strong, but not necessarily the heart.
He had vaguely guessed from conversations with the Myouju that he had a sharp tongue, but he didn't know he could pour out such fluent abuse. No, abuse? He doesn't understand half the meaning, but can this count as abuse? Still, since it stabs the heart, it probably counts as abuse.
Tears welled in Kokushibo's middle eye—the eye he had since he was human—who only knew Young Moon who followed him around clumsily saying "Teacher! Teacher!" in a faltering voice after he started speaking.
Kokushibo, who hadn't particularly cared about his demon appearance, showed agitation for the first time, thinking "Could my appearance be scary?" His movement stops. How the boy received this, he also stopped attacking and caught his breath, entering a brief recovery period.
A demon's form is the appearance one wishes to become. He thought these eyes increased to six were probably to chase Yoriiichi's movements that could only be thought of as having six arms, so he had accepted this form. Though even increased to six, he ultimately couldn't chase his younger brother's movements.
He never particularly felt uncomfortable with this face, and since he abandoned a life mingling with the secular world, it didn't matter at all even if it was a bizarre appearance distant from humans. Thanks to that, his transformation is clumsy and he quickly reveals his demon form like this if careless. But he didn't consider it a particular problem.
Is having six eyes on a human face that scary? His master Kibutsuji Muzan gave it high praise. To the extent of being told to absolutely not reduce the eyes and remain as he is.
When his aging younger brother shed tears saying "How pitiful, elder brother," was it perhaps not lamenting this body that became a demon, but pitying the ugly appearance with six eyes? What's that, it's annoying.
Recalling old matters, Kokushibo's mood became agitated for a moment. The killing intent that slightly leaked made him, hiding in the bamboo grove, gulp and swallow his breath.
Despite his young age, the boy well understood the difference in strength between the heteromorphic demon and himself. While confident escape was confirmed and entrusted himself to the bamboo grove, he was realizing that demon was stronger than expected and that he was at a disadvantage like this.
Thanks to being looked down on as a child and the opponent holding back, he had barely managed to fight equally until now. But if that demon reveals his true intent, his home ground bamboo grove would instantly become wasteland.
No, but that demon, no matter how you look, is definitely the type that shoots destruction beams from its mouth. The type that would burn down the entire bamboo grove area and more. Such a good, splendid bamboo grove for fighting becoming wasteland? An act that would enrage the old bamboo cutter. Anyway, must not let him open his mouth. The boy resolved.
Cannot shrink back in fear.
Yes, don't stop your hands to survive.
──Still. Still, if asking someone for help in such a hopeless situation is allowed. There's only one person the boy wants to call.
"Teacher…!"
A whispering like a prayer melting into the night.
With that one word, Kokushibo's heart was pierced.
Yes, come to think of it, Young Moon followed me well. It's just that he doesn't recognize me because of my demon form now, but if I reveal my identity, wouldn't he obediently let himself be captured? Holding faint hope, Kokushibo opens his mouth. The boy seemed to startle again with a 'gasp,' but Kokushibo didn't hear.
"Young──"
A bamboo spear rushes toward his face as he takes a step.
Cannot speak.
"Hey──"
Evading the bamboo and opening his mouth again, this time a bamboo whip lashes down from above toward his face.
Cannot speak.
"Young──"
The moment he tries to call that name without giving up, numerous bamboo stems fired rapidly like arrows.
Cannot even call the name.
Whether it's his imagination or not, the speed and power are on a different dimension from before. Kokushibo narrows his six eyes and sees through the boy's young body—his pulse and blood circulation have accelerated to an abnormal degree. Could it be, could this be.
"Mark──"
"Shut up! Who'd let you shoot a destruction beam! I'll protect this bamboo grove!!"
Finally, bamboo flies toward his mouth.
Let me speak. Please let me speak.
＊
At dawn, seeing Kokushibo appear in the Infinity Castle with the sound of a biwa, Kibutsuji Muzan frowned.
"Kokushibo, you… why are you covered in bamboo leaves."
"Encountered… a Bamboo Breathing user..."
"Bamboo? Which Breathing does that derive from?"
"Of course, from Moon Breathing."
Why do you sound somewhat proud?
Hearing the word 'bamboo,' what Kibutsuji Muzan recalled was his friend who, inspired by the Tale of the Bamboo Cutter that Muzan had recited, went wild saying "Let's test how far bamboo can be used in ten thousand things!" and rummaged through nearby bamboo groves, once earning the rumor of being the 'Bamboo Grove Destroying Fiend.' Eh, no way.
When Kokushibo goes into the human world in his transformed appearance, Kibutsuji Muzan basically tries not to look into his field of vision.
Kokushibo's transformation is nearly identical to his appearance during his human days, and Kokushibo is Tsugikuni Yoriiichi's twin brother. If that face happens to be reflected in a mirror or water surface or such, Kibutsuji Muzan's SAN value will undoubtedly drop significantly. A promised fumble of defeat. Do you understand?
Therefore, Kibutsuji Muzan, who hadn't looked into Kokushibo's field of vision, doesn't know. The fact that the Bamboo Breathing user he speaks of is his friend.
Thus they miss each other today too. Surely they'll miss each other tomorrow as well.
For reference, from this day on, Kokushibo devoted effort to mastering perfect transformation, and as a result, Kibutsuji Muzan's SAN value would be dug out wildly with an excavator, but that is another story.