Bidding farewell to Tanjiro and Tetsuya, Seiichi planned to return to his assigned room for some well-deserved rest.
He stretched lazily and yawned. Although he hadn't been running himself during the journey, the distance they had traveled was still the same. Roughly speaking, it was as if he had been bustling about for that entire length of time.
I'm just deceiving myself with this logic.
Taking out his new Nichirin Sword, he carefully drew it from its elegant sheath. Seiichi's reflection appeared clearly on the pristine white blade. He was truly satisfied with this exceptional weapon.
Not only was its quality hard and durable enough to withstand the extreme high temperatures of a Red Nichirin Sword, but its spiritual attributes were also perfectly balanced and neutral. This meant the Nichirin Sword itself wouldn't suffer any damage when switching between different Breathing Styles.
After admiring and testing it for a while, Seiichi decided to continue his training routine. Sun Breathing techniques, Red Nichirin Sword mastery, and his Viod Breathing Style were all practiced one by one, and his proficiency with each was steadily increasing every day.
Now, Seiichi had only one major technique left to master: the Transparent World. The Transparent World was similar to the Byakugan ability from the ninja world. They were actually very comparable in function.
Both abilities allowed the user to observe an opponent's bones, muscles, and internal energy pathways like an X-ray machine. More importantly, they significantly enhanced the user's ability to see through an opponent's movements and identify their critical weaknesses.
If Breathing Styles greatly enhanced a swordsman's physical strength and endurance, then the Transparent World greatly enhanced a swordsman's perception and awareness. It allowed the user to see through an opponent's entire body structure, predict their future actions, and dramatically increase the speed of both attacks and evasions.
Simply put, it completely maximized dynamic vision and reaction time.
The key to successfully activating the Transparent World lay in achieving precise breathing patterns and controlled movements, unleashing maximum power with minimal physical action. When properly activated, the swordsman needed to shut off their other senses completely.
Through repeated correct actions and intense focus, they could achieve a transparent state of awareness to observe the opponent's internal body structure, then strike with lightning speed to defeat the enemy in a single decisive blow.
The concept of repeating specific actions until they became instinctive was very common throughout the Demon Slayer techniques, but for Seiichi, this traditional approach didn't really matter.
For someone like him, who possessed the Close to the Way ability, learning new techniques was never particularly difficult. However, without a proper reference or teacher to guide him, inventing techniques from scratch might take some additional time.
It was just like with the Red Nichirin Sword technique, which he had gained insight about from observing the crimson tip of Tanjiro's blade when he cut Upper Moon Six.
However, it shouldn't take much longer to figure out, Seiichi thought confidently. Close to the Way is truly an incredible advantage. Give me another month of focused training, and I'm confident I could make Muzan run around frantically trying to escape in this world.
While Seiichi was peacefully resting and planning his training, the Infinity Castle on the other side was anything but calm.
"Gyutaro is dead."
Muzan, holding a test tube filled with dripping liquid, carefully observed his latest experiment. He put down the glass container, slowly raised his head, and his terrifying scarlet eyes shifted downward, staring directly at the Upper Moon demons below.
"You have disappointed me far too much!"
He swung his left hand violently, smashing all the bottles and glass containers on the laboratory table. His face gradually became increasingly ferocious and twisted, and he pressed his right hand against his temple in obvious frustration.
"For hundreds of years, you have accomplished absolutely nothing!"
"It seems I have been far too indulgent with you because of your status as Upper Moons."
The atmosphere in the castle became chilling to the absolute extreme.
The first to speak was a creature that could barely be called a person, or rather, a demon with an unnaturally excited expression. He was far from human in appearance. His upper body was humanoid, with normal arms and a torso, but his lower body was merely a decorative pot.
Where eyes should have been on his face, there were two green-lipped mouths instead, while his forehead and actual mouth contained eyes. The golden irises of his upper eyes were engraved with "Upper Moon," and the eyes below his face were engraved with "Five."
It was none other than Upper Moon Five—Gyokko.
"Muzan-sama, I have found the Demon Slayer Corps' weapon forging location, please..."
"Hmph, boring, utterly boring."
Before he could finish speaking his report, in an instant, Gyokko's severed head appeared in Muzan's powerful hand. Thick blood poured out, and the pot-like body had already fallen to the ground like a lifeless corpse, fresh blood flowing across the floor.
"What I want is news of the Blue Spider Lily!"
He directly threw Gyokko's head down with disgust, blood splattering everywhere across the platform. Muzan turned around, glanced with contempt at the trembling figure prostrate on the ground, and then disappeared back into the darkness.
"After verifying the information, Gyokko, you and Hantengu will go."
"Yes, Muzan-sama!"
Gyokko, who had just reattached his severed head to his body, said with obvious excitement. Afterwards, he looked at the pathetic figure lying on the ground nearby.
It was a hunched old man, but on closer inspection, he clearly had a demonic appearance, with a large bulbous growth on his forehead and two curved horns protruding from his head. Strangely, his eyes were not engraved with "Upper Moon" and the corresponding number like the other Upper Moon demons.
Licking his lips, he had no intention of leaving the Infinity Castle immediately. He retracted his lower body and watched the two figures on the elevated platform with obvious curiosity.
One was a white-haired man sitting casually on the ground, smiling with the pure joy and innocence of a child, swaying from side to side like a roly-poly toy. He had off-white hair and wore a black cloak. His rainbow-colored irises were engraved with "Upper Moon" and "Two" respectively.
The other was a man standing perfectly straight, with his back turned to Douma. He had short peach-pink hair, golden eyes, pale skin, and his entire muscular body was covered in intricate dark blue tattoos. Besides the engraving of Upper Moon Three in his eyes, the rest of his expression was filled with obvious displeasure.
"Oh my, what interesting news is it, Gyokko?"
No longer looking at Akaza, Douma stood up and approached Gyokko with curiosity, even poking the pot body with his finger playfully.
"Did Muzan-sama give you any specific orders?"
A cold voice came from behind.
BANG!
As soon as the words fell, Douma's head was directly smashed by a powerful punch, his upper skull exploding into chunks of flesh and bone. Akaza had appeared behind them at some point, his raised right hand covered in blood, clearly indicating he was the one who had struck.
WHOOSH!
A splash of blood, and Akaza's right hand was directly severed horizontally in retaliation.
"You went too far, Akaza."
A calm voice sounded directly in Akaza's ear. His pupils contracted slightly in surprise. Standing behind him was a tall man with long, deep red sideburns and a high ponytail.
"If you are dissatisfied, you can initiate a Blood Battle for Ranking."
The face that turned to look at Akaza had a full six eyes. "Upper Moon One."
"Oh my, Kokushibo-dono, I was just playing with him. Besides, even if he initiated a Blood Battle for Ranking, he wouldn't be a match, right, Akaza?"
The flesh fibers on his head intertwined and regenerated, instantly healing his injuries. Douma said this with his characteristic smile.
Akaza's veins bulged with anger, but he made no aggressive move.
"Abandon that boring persistence, Akaza." Muzan, slowly emerging from the darkness, had returned to observe them.
Akaza immediately knelt in respectful salute, Douma also sat up straight, and Kokushibo bowed slightly in acknowledgment.
"Muzan-sama, why..."
"Because I changed my mind." Muzan's deep gaze revealed no emotion whatsoever. Only the trembling sound of Hantengu remained in the air.
Back at the Swordsmith Village.
"The hot springs here can also heal injuries. The world is truly full of wonders."
Tanjiro and Seiichi were on their way to the mountain hot springs. Seiichi had been pulled along by Tanjiro's enthusiasm. However, he was actually half-willing to go, as he genuinely wanted to try the experience of soaking in a natural hot spring.
Just as they reached the stone steps at the foot of the mountain, they heard a clear voice calling from somewhere above.
"Tanjiro! Seiichi-kun!"
Mitsuri, wearing a colorful yukata, ran down the steps with obvious excitement.
"Listen to me, listen to me! I was just ignored by someone, boo hoo hoo."
Mitsuri had a tear-streaked face and hugged both of them tightly, spinning around in a circle.
Seiichi, feeling a bit dizzy from being shaken around, laughed helplessly. The peaceful life in Swordsmith Village begins now.