Antarctica
In a vast wasteland covered entirely in snow, a being flew at nearly the speed of sound.
He had red eyes and grey hair, with two goat-like horns protruding from his head. Two massive blood-red wings extended from his back. One of his eyes had the number one engraved in it. His upper body was bare, revealing strange markings across his chest and abdomen.
After a few minutes, a massive castle came into view, floating in the middle of the wasteland. The structure stood nearly 600 meters tall and looked ancient.
The being swiftly landed at the entrance and lightly knocked on the massive metal doors.
After a few seconds, the gates opened, revealing two hulking demons—each nearly three meters tall—with enormous greatswords strapped to their backs.
"Lord Dusk."
Both demons bowed slightly.
Dusk gave a small nod and walked past them.
Soon, he entered a grand hall and spotted a pale woman with a grayish complexion. She had sharp, blue-stained nails and striking red lips that contrasted against her skin. Her dark brown hair flowed down to her waist in slight waves, with two chin-length strands framing her face. Long bangs partially obscured her eyes.
She wore a plain black kimono with white lining, secured with a pale brown striped obi, along with white socks and no shoes. In her hands, she held a four-stringed wooden biwa and a large bachi pick.
"Biwa woman, I want to meet Lord Muzan."
Nakime remained silent. After a moment, she plucked a string.
The floor beneath Dusk vanished.
Dusk found himself inside a room filled with mountains of books.
He walked forward until he saw a beautiful woman working with various chemicals. She had ruby-red eyes and silky black hair tied into a braided bun. She wore a black kimono with red-lined edges.
"My Lord."
Dusk immediately dropped to his knees, his body trembling under the overwhelming pressure radiating from her.
After half an hour, the woman set down her test tubes and glanced at him.
"Did you complete your mission?"
Dusk raised his head.
"Yes, my Lord. I traced every individual bearing the Kawahire name across Japan."
"None remain."
"Hm."
"And any information on the Blue Spider Lily?"
"I apologize, my Lord. I have searched for years, but there is no trace of that flower."
The woman walked toward a bookshelf and picked up a book.
"Move your base of operations to China. Continue your search there."
"Understood."
The floor shifted once again, and Dusk disappeared.
"Yama."
A shadow stirred behind her, and a dark figure emerged, his entire body cloaked in darkness.
"My Lord."
"Tell Douma to reduce the number of Pillars in Japan. He may take the Second Legion with him."
"Understood."
Yama vanished into the shadows.
The woman turned back to her table and resumed her work with the test tubes.
-
The sun rose.
In an open field, a silver-haired boy stood with his eyes closed. A sword rested at his waist. Five wooden puppets were placed at a distance around him.
He unsheathed his sword and took a stance.
'Flame Breathing: First Form.'
Jin opened his eyes. His breathing steadied.
Flames began to dance along his blade, and the temperature around him rose.
He dashed forward. Midway through, he swung his sword horizontally. A flaming arc shot forward, decapitating three puppets instantly.
'Third Form.'
Jin changed direction, leaping high into the air. His blade came down in a vertical slash, releasing a blazing strike that split another puppet in half.
'Sixth Form.'
He rushed toward the last puppet, spinning as he curved his blade. In a single motion, the puppet was cleaved into three pieces.
*Heavy breathing
"Hah… hah… hah…"
Jin stood there, leaning on his sword. The ground before him was scorched, and the remains of the puppets had already turned to ash.
After a few moments, he sat down cross-legged and began circulating universal energy through his body.
'Rengoku-san said that each time we circulate this energy, a small portion gets stored in our cells, gradually strengthening our body.'
'My control has improved significantly over the past four days.'
'Now… let's try directing the energy to my eyes.'
Despite his confidence, sweat formed on his forehead.
He closed his eyes and carefully guided the energy upward.
'I can feel something changing… but it's not painful… It's soothing.'
Jin slowly opened his eyes.
They had turned completely white.
He looked around—and immediately noticed an improvement in his vision.
Focusing on a distant tree, he narrowed his eyes.
'Woah…'
'This is incredible…'
'I can even see ants on the branches.'
Then, something else caught his attention.
A faint green aura surrounded the tree.
Jin quickly withdrew the energy, and his eyes returned to normal.
'I need to test this on humans.'
He stood up, sheathed his sword, and ran toward the headquarters.
Along the way, he observed passersby. Most had faint green auras, while some elderly individuals had almost none.
Soon, he reached the headquarters and began observing demon slayers.
Unlike ordinary people, their auras were vivid.
'The colors match their breathing styles…'
'Dark blue for Water… light red for Flame… pink for Love… light blue for Flower… purple for Thunder… dark green for Wind…'
After some observation, he realized he could roughly gauge their strength based on their aura intensity.
He entered the headquarters and headed toward the training grounds. There, he spotted Commander Yuji, training cadets.
Activating his eyes again, Jin immediately noticed—
Among all the slayers he had seen so far, the commander was the strongest by a significant margin. His aura was a light shade of purple.
'A Thunder variant… probably Sound Breathing.'
'Now… let's find Rengoku-san.'
'I want to see what a Pillar's aura looks like.'
After some searching, he found Rengoku exiting the cafeteria.
Jin immediately channeled energy into his eyes.
*Thud
Jin collapsed onto all fours, panting heavily, sweat dripping from his face. His eyes were tightly shut.
'That…'
'That is insane…'
'He's a monster.'
Rengoku's aura was like a raging hurricane with no end in sight—vast, violent, and impossible to measure.Even a single glimpse was enough to crush him.
Now he understood the level of power required to survive in this world.
If a Pillar's aura alone could overwhelm him like this…
Then what about the Upper Moons, who were said to be even stronger?
Jin clenched his fists and slowly stood up.
His eyes were filled with determination.
'Someday… I will reach that level.'
'No… I will surpass it.'
_________
Note:
The Upper Moons have their rank engraved into both of their eyes, while the Lower Moons only have one of their eyes engraved. Dusk is a lower moon rank 1.