After the 'You bastard Yoriiichi, I won't forgive you ~ Destroyer of the Love and Jealousy Training Post~' incident, Michikatsu-san began looking out for me in various ways. Specifically, accompanying me in training.
Michikatsu-san was quite Spartan and had his own training, so he didn't teach me everything individually; above all, he was the 'watch and learn' master type, so I'm watching and learning while panting.
But it's kind that he points out problems with my posture before they become habits. And then he sentences me to additional training. Strict.
Oh right, I also learned Breathing. Though it's called Breathing, it's not about inhaling oxygen and exhaling carbon dioxide. It's a technique of inflating the lungs to improve blood circulation and gain physical abilities to face demons; that is Breathing.
Using this to move my body, wow. I've become able to put up a fairly decent fight even with older swordsman uncles. Not fairly and squarely, but with a hit-and-away strategy utilizing quick footwork.
But I still just get slammed by Yoriiichi-san! I keep challenging him again and again, but it's nothing but repeated defeat!!
Because I charge in with an overly never-give-up attitude, Yoriiichi-san gives off a perplexed air, but who cares!! Even if I lose a hundred times, I might win on the hundred-and-first!! You think I'll let Toki-chan's grudge rest?! But I can't even follow his movements, so frustrating!! Damn it, let's train harder!!
As I was devoting myself with such zeal, they said the time had come and even gave me a sword. Taking me to a place called the swordsmith village, I received a custom-made weapon in a special size tailored for me, a child.
They say Nichirin blades change color for each user, and the dyed color indicates aptitude for a certain Breathing style. What kind of fantasy is that? What kind of over-technology is this?
Breathing itself was recently devised and is still under research, so the details are unknown, but they said Breathing has types with attributes like lightning, fire, water, and such. Using this to swing a sword makes effects sparkle. Awesome. I admire it.
The swordsmith uncle said, "Get used to it in your hand before returning," and guided me to the bamboo forest inside the village, so I trained without refusal.
Since any bamboo forest existing in this world is practically my front yard, my tension rose slightly and I excitedly rampaged holding the sword in one hand, and before I knew it, I received a persistent encore from a guy in the bamboo forest: "What was that movement just now?! What kind of movement?! Amazing! One more time!"
The guy muttered something while staring at my movements. Huh, scary.
I was observed the entire time I was in the village. Huh, scary (second time).
But he gave me tons of sweets as a souvenir when parting, so I think he's probably not a bad person. I heard he's the village's master craftsman.
For reference, my blade is a light purple. It dyed the same color as Michikatsu-san. So now I'm being instructed by Michikatsu-san.
What Michikatsu-san wields is none other than 'Moon Breathing'. The name is good. The fact it's the moon is very good. Totally cool. I'm no longer a kid who admires straightforward attributes like 'Courage 100x Passionate Red!'. Cool & Dark is the world's trend.
Above all, Moon Breathing's effects were cool. The stronger the Breathing, the more distinct the effects appear, and the moon's effects were totally awesome with a crescent moon barrage. I want to show Muzan-kun too. In my previous life, he was sickly and couldn't go out into sunlight, so we often watched the moon together.
The moon's effects, which were faint at first, also began to take on轮廓 as I repeatedly mimicked Michikatsu-san's movements. Feeling the tangible reality that the more I train, the stronger I become, I immersed myself in training and repeated it.
Having learned Breathing and obtained a Nichirin blade, the day I receive my first mission must be nearing too. So I trained even harder to be ready whenever that day comes.
All of that is for Muzan-kun. Because Muzan-kun is the leader of demons, meaning the final boss for the Demon Slayer Corps.
If his location is revealed and it's 'Alright, move out!' time, a development like 'You're weak, so guard the house!' would be an unsightly scene I couldn't bear to watch.
Therefore, I must become strong and gain everyone's trust. So that when Muzan-kun is found, I can follow there.
For reference, roughly five hundred years have passed from the Heian era I lived in to this era, but I didn't worry at all that Muzan-kun might have forgotten me.
Because Muzan-kun had excellent memory to the point of saying things like, "You, I heard you broke the mansion's sliding screen again. Just how many times is this? Twelve? Don't exaggerate, it's fifteen. Twelve was the number of times you blew away Father's coffin with a ball, anyway."
They say physical abilities improve when becoming a demon, so surely the brain does too. Muzan-kun must have achieved evolution with even higher intellect. Then he'll surely remember my appearance clearly!
Moreover, I have a full-blossomed smile that even Muzan-kun acknowledged, saying "Just looking at it makes most worries feel stupid"!
If I show that, even though I can't speak now, Muzan-kun will recognize me!
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──By the way.
The boy perceives himself as 'a mischievous boy with a bright, cool smile~!'
But in reality, due to long prison life, he couldn't properly use his facial muscles, resulting in a stiff, expressionless face.
The only one unaware that his own expression doesn't move a bit, to the level of rigor mortis, is the boy himself.
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'Nine hundred ninety-seven, nine hundred ninety-eight, nine hundred ninety-nine, thouuuuusand!!'
"Don't tilt your center of gravity. From the beginning again."
'Aaaaaaah!! Michikatsu-san is totally Sparta!!!'
No change in expression, and he can't voice it, but this guy's thoughts are easy to know. More than words, you can vaguely guess what he's thinking through sense. For example, now he's screaming a choked scream inside upon being told to redo his downward strike training.
Still expressionless, but the boy differed from Yoriiichi in this aspect. With him, you truly couldn't grasp what he was thinking at all. His eyes were abysses and his expression always calm. To add, his mind was the deep sea. With unknown fish swimming in it.
'My arms! My arms are falling off!! It's hard!! Aren't my arms passing away tonight in a muscle-pain sense!! Feels like my muscles are dying of overwork at a cellular level! Please let me rest, even if it's not paid leave, please give me refreshment leave!!!'
"Can you become strong with lukewarm training."
'You're right!!! Die, my muscle fibers!! Muscles have no Labor Standards Act, work, cells!!!'
Beside the boy gripping the wooden sword again with calloused hands, I too began downward strike training. Also serving as a model for the boy.
When time allowed, I watched over the boy's training like this. While making soundless complaints, the boy was greedy to become stronger, and when I swung my sword beside him, he peeked at every single movement.
By the time he learned all the basics, he had also mastered Total Concentration Breathing, and being that promising a child, I vividly remember everyone being excited with anticipation about what color his Nichirin blade would take.
If an existing color appeared, a swordsman of the same color would teach him, and if a new color appeared, Yoriiichi would guide him—that was the unspoken rule—but the boy's blade returning from the village was a purple like wisteria flowers.
Dyed the exact same color as Moon Breathing, the role of teacher fell to me.
A derived Breathing that could never catch up to Sun Breathing no matter how much training was repeated. Something recently named 'Moon Breathing' with a twisted meaning. The boy accepted it with apparent joy. What about such a pathetic Breathing could make his heart flutter so, I couldn't understand at all.
The boy remembered my movements well. Even though it wasn't meticulous instruction teaching each detail, but simply learning by watching through sparring.
Staring intently at every single form I used without missing one, following meticulously with his sword, making it his own as if pouring water from vessel to vessel. Day by day, his swordsmanship sharpened. The thin moon slowly, slowly filled.
Watching that, a strange refreshment would rise in my chest, which had been clouded by hatred and jealousy towards my younger brother.
"He's really working hard, the Young Moon (Osanatsuki)."
During a training break, while the boy left his spot to quench his thirst, the one who spoke to me like that was Enju.
Young Moon was the boy's nickname. Having been raised as a mountain sacrifice with no name, he began to be called that among the swordsmen due to his young age and being a Moon Breathing user. Everyone was thinking of giving him a serious name rather than such a nickname, but due to circumstances, it's on hold.
The reason is that the boy, namely Young Moon, had extremely fierce likes and dislikes regarding names.
When the topic of giving him a name came up, the first to raise his hand was the Lightning Breathing user. A small man appointed as Myouju.
Red eyes, white hair. A small being associated with the moon. Drawing a parallel to that, he suggested 'Rabbit'. That was the start of everything. The biggest mistake was calling him 'Rabbi-chan' or such as if teasing him. Naming him after a fluffy, cute small animal that a girl would like, and on top of that adding '-chan', made the angry Young Moon kick Myouju's butt outright.
With the premise of being 'second to Yoriiichi', but when he, the fastest among the swordsmen, chased with anger that seemed to pierce the sky, Young Moon ran away as swiftly as a rabbit.
Young Moon, who ran out of the mansion and fled to the nearby bamboo forest, was truly, extremely strong.
I didn't see the scene, but they say he didn't allow even his shadow to be stepped on against an elder with abundant combat experience and a strong foe. Myouju, who was also a Mark bearer, returned from the bamboo forest with a trembling body.
"Is that brat the darling of the bamboo forest???" were his words, covered in bamboo leaves.
And then, Suuju, who kindly suggested an alternative, "Comparing bamboo to the moon, how about the name Kaguya?", was the next victim. A boy wouldn't like the name of a weak bamboo princess.
He who boldly stepped in to retrieve Young Moon, who had holed up in the bamboo forest, came out one and a half hours later, also covered in bamboo leaves. Staggering. His face paler than his blade, he muttered "Bamboo Breathing…" and fell silent.
Strange. What I taught should have been Moon Breathing.
Even when pressed for what happened, both kept their mouths shut.
This is over. Their spirits were broken to the root.
The third one to head to the bamboo forest, Enju, came out with splendid bamboo shoots tucked under both arms, his heart fluttering. By not spouting unnecessary words and usually doting on Young Moon in various ways, he saved his life and even received gifts. An exceptional treatment compared to the first two who sacrificed their butts and hearts.
For reference, Enju was so distracted by the bamboo shoots he forgot his mission to bring Young Moon back.
There was also a suggestion to wait for Yoriiichi's return from his mission and capture him then, but if the child who toyed with the Lightning and Water swordsmen were caught that easily, the two men's pride would suffer. Especially since Suuju's spirit was just broken; breaking him again would be cruel. He would shatter.
In the end, I brought Young Moon back. Seeing Young Moon, who returned obediently led by my hand without stubbornness, Suuju wept, pounding the ground, "If only we had sent you from the beginning!" I can well imagine the feeling of goodwill going awry and suffering unnecessary damage.
It took a week for Suuju's broken spirit to heal, and a month for the maple-leaf-like swelling on Myouju's butt to subside. For reference, the bamboo shoots Enju received all disappeared into everyone's stomachs overnight. Comprehensively speaking, the damage suffered that day was immense.
Because of such an uproar, everyone became cautious about giving the boy a name, and it was settled with the nickname Young Moon for now.
Resuming the story.
"To endure such strict training so well, Lord Michikatsu truly has a good successor."
"Successor, you say?"
"Hm? Was that not your intention in teaching him?"
The Flame Breathing user smiled, with a gentleness unimaginable from his appearance in battle.
"Young Moon surely admires you, Lord Michikatsu. He always watches your sharp sword with shining eyes."
"Doesn't he do that with everyone? That guy is greedy to become stronger. Unbound by Breathing, he watches any sword intently."
"Well, it seems you don't know. I may not connect with Young Moon as well as you do, Lord Michikatsu, but I know with what feelings he looks at you."
His voice was filled with conviction. His eyes seemed to gaze at some distant place.
"A child following parents, a younger sibling chasing an older brother, a disciple looking up to a master… That child's eyes are filled with such admiration."
This swordsman, who inherited the mission of demon slaying through generations, had his older brother eaten by a demon. That's why he became a demon slayer.
Was the admiration reflected in his distant gaze a memory? A lonely light dwelled in his yearning for his brother.
"Lord Michikatsu. How about giving him a name soon? If it's a name given by you, that child would surely be pleased."
The swordsman gave me a beaming smile. Unable to refuse that smile, I vaguely said, "I'll think about it," and Rengoku smiled even deeper, as if having obtained a promise.