(This is the prelude to his arrival to Demon Slayer world…I recommend reading it…but you can skip to chapter 2 if you like.)
***
In the Milky Way — Spacetime Management Center
"Warning! Warning! Void Worms are destroying the Time Gate! History will be rewritten! Eliminate them immediately—eliminate them immediately!"
"Attention all units! Activate the Stardust Burst Cannons at once! Exterminate the Void Worms!"
From the shattered void, colossal mechanical worms burst forth one after another. Across the expanse, nine spacetime patrolmen clad in black dark-matter armor battled the monstrous creatures with grim determination.
"This is Number Seven! Requesting immediate backup—my energy reserves are almost depleted!"
"Number Nine reporting! My shield has collapsed! The Void Worms are about to breach our defenses!"
"Number Two requesting aid! My energy output won't last another hour!"
"Ammunition Unit Five is nearly spent! Requesting reinforcements—repeat, requesting reinforcements!"
…
"Station Chief, all patrol units are calling for support!" A female officer in a blue-and-white combat suit reported, her voice tense. "The Void Worms' assault is far more intense this time! Several of our support teams have already been devoured!"
The stationmaster slammed his fist onto the console, eyes blazing.
"Those wretched things just won't die! Luo Li—dispatch the Guard Division at once to reinforce all patrol units!"
The portal must be protected. If it were destroyed, the time tunnel would collapse. History itself would unravel—and humanity could vanish entirely.
"Yes, sir!" Luo Li answered.
"Calling all Guard Units! This is Spacetime Management Headquarters! Provide immediate support to all patrols and defend the Time Gate at all costs!"
"Squad One, received!"
"Squad Two, received!"
"Squad Three, received!"
***
"This is Patrolman One! Urgent report! I've located the Void Worm Mother—but my energy and ammunition are nearly gone! I can't continue pursuit—requesting backup!"
"Number One, hold on! Reinforcements are en route! Just hold a little longer—"
Before the stationmaster could finish, a new voice—young but calm—echoed through the channel:
"Leave it to me. Number One, focus all remaining energy into a defensive shield to protect your gate. I'll arrive in three minutes. This time, it won't get away."
The stationmaster froze. "That voice… Zero?!"
Number One gasped. "Number Zero has awakened?"
Luo Li's eyes widened. "Impossible—Zero went into deep sleep after the Great War centuries ago! How could he be awake?"
***
Centuries earlier, an unknown virus had infected the Spacetime Management System, causing catastrophic malfunctions.
A colossal mechanical worm—its body stretching for over a thousand meters—had torn through the void, leading an army of its spawn to ravage several spacetime portals. Each portal connected to a different era of human history.
Once destroyed, history would be rewritten. Humanity itself could cease to exist.
The station chief led hundreds of guard units in a desperate defense, but the swarm was too vast. Just as hope faded, Time Patrolman Zero appeared—flanked by nine elite patrolmen. Within minutes, they obliterated the swarm. Zero himself nearly destroyed the Worm Mother.
But in the final moment, the Mother unleashed a surge of anti–dark-matter energy toward the main station.
If it struck, all existence would dissolve into nothingness.
With no other choice, Zero abandoned his pursuit and used his own power to open a wormhole, devouring the destructive energy before it could reach the station. The Worm Mother escaped, but Zero and the others suffered grievous damage, their bodies and consciousness sealed into deep stasis.
To fill the void they left, the station chief later appointed their descendants as the next generation of Time Patrolmen.
Zero, however, left no successor. He'd simply said, "Being alone is fine."
Everyone at the station knew the truth—he had forgotten much of his past.
Since humanity entered the technological era millennia ago, dark-matter energy had granted them near-immortal lifespans. Though eternally youthful, Zero had lived for countless centuries, his appearance frozen at sixteen.
…
"What is that?" Number Nine muttered, eyes widening as a streak of red and blue light approached at lightspeed.
"Stationmaster! Unidentified object incoming! Dark-matter density is off the charts—requesting assista—"
BOOM! BOOM! BOOM!
A series of explosions ripped through the area. In an instant, the Void Worms surrounding Number Nine disintegrated into nothingness.
"What… what just happened?" he whispered, stunned. He had fought for hours just to hold them back—and yet the swarm had been annihilated in seconds.
A figure landed before him—armored in red-and-blue dark-matter plating. A small, floating robot shaped like a tiny girl hovered by his shoulder.
"You're Number Nine of this generation?" the newcomer asked.
"Yes! I am. My father fell into stasis a century ago, so I've taken his place."
The young patrolman stared, bewildered. Every patrolman wore dark-matter armor—but this one's design was completely different.
Then realization struck. Zero. The legend.
"This is Zero. Reinforcements are on their way. Repair the shield and guard this sector. Leave the rest to me."
Without another word, he took flight toward the next battlefront.
"Act according to Zero's orders!" the stationmaster's voice barked through Number Nine's earpiece.
"Yes, sir… So that's the legendary Zero…"
***
"T0, have you finished analyzing the Mother's data?" Zero asked as he flew through the debris.
The small floating robot blinked to life. "Affirmative, Master. But according to Number One's transmitted data, the Mother's new body contains something extremely dangerous!"
"What is it?"
"Unknown energy fluctuations—volatile enough to trigger large-scale collapse. Master, I have a bad feeling about this!"
Zero's voice hardened. "Understood. A hundred years ago, it escaped. This time, it won't."
***
"Sorry to keep you waiting, Number One. What's the situation?"
"Zero! You actually woke up!" Number One laughed. "That thing's nearby—seems to be building up something massive. I've sent you the coordinates. Be careful, kid—it's not like last time. It's stronger."
"Got it. I brought backup energy cells and dark-matter ammo. I cleared the nearby Void Worms on the way. Focus on repairing your shield."
"Understood. Just promise me—if things go wrong, retreat this time."
Zero gave a faint smile. "I'll keep that in mind."
He soared away toward the coordinates.
A bit later…
"According to the data, it's hiding here," Zero muttered.
"T0, scan ahead."
"Scanning… Target located, Master. It's concealed within that meteorite cluster."
"So this is your den. Not this time."
The Void Worm Mother let out a furious roar, as though recognizing the one who had scarred it centuries ago.
"Still alive, huh? You disgusting thing… Let's finish this."
He drew a massive, futuristic sniper rifle from his nanospace—black and red patterns pulsing across its 1.5-meter frame. The weapon hummed with dark-matter energy, the scope glowing crimson.
"Die."
BOOM!
The recoil sent Zero sliding backward a few meters. The armor-piercing round tore through the creature's core.
The Worm Mother shrieked but didn't counterattack. It was… waiting.
BOOM! BOOM! BOOM!
Three more rounds slammed into its body.
"Something's wrong!" T0 cried. "Master, I'm detecting huge concentrations of anti–dark-matter energy and tritium inside its core! If released—it'll form a black hole! The entire sector, even headquarters, will be destroyed!"
"Is there a way to stop it?"
"Yes—but only one. If we focus every patrol's energy attack on a single point, compress it with the dark-matter engine, and detonate it within a wormhole, it might neutralize the blast."
"That requires a host with a dark-matter engine, doesn't it?"
"Yes, Master—but—"
"Then I'll do it. My armor's equipped for that."
"Master, no! The energy overload will kill you! You'll—"
"T0, enough. I have nothing left to lose… except you. If I don't make it, find Luo Li—she'll take care of you."
"B-but—"
"No more words, T0. It's decided." He switched channels.
"This is Zero to Main Station."
"Stationmaster here."
"Connect me to all patrol units. I'll explain what must be done…"
***
"No! Absolutely not!" Number One roared. "You idiot, do you want to join the others in stasis? Numbers Three, Four, Six, and Nine are gone already! Haven't we lost enough?"
"Only I can do this!" Zero replied sharply. "If I don't—history will collapse. Humanity will vanish!"
"Damn it…"
"Stationmaster, initiate the plan. I'm ready."
A heavy silence. Then a sigh. "Understood. Luo Li—talk to him."
"Mm."
Her voice came through the channel, trembling. "Zero… do you remember your name?"
"My name? Sorry… it's been too long. I've forgotten."
"Your name is Bai Yue," Luo Li whispered. "You saved me once—long ago. You might not remember, but I never forgot. I remember everything about that day… and I remember you."
"Bai Yue…? I see. So that was me."
"Yes. And before you go… there's something I need to say. I… I-Ive always liked you."
Zero's heart stirred faintly—but he pushed the feeling aside. "Luo Li… I'm sorry."
"It's alright. Just promise me you'll come back alive."
"I'll try… No—I will."
***
"Zero, prepare for countdown," the Stationmaster ordered.
"Ready."
"Countdown: ten… nine… eight… seven…"
"T0, get to safety," Zero said quietly. "Go to Luo Li."
"No! I'm staying with you. You've always been like family to me. I won't leave you now!"
"You stubborn child… Fine. But do exactly as I say."
"Good!"
"Three… two… one… FIRE!"
The combined energy of every patrol unit converged.
"T0, activate the dark-matter engine!"
"Engine active!"
The engine on Zero's back flared, absorbing and compressing the combined energy.
"Open wormhole—target locked!"
A vast wormhole opened, dragging the unprepared Void Worm Mother into its vortex. The pressure was immense—every second tested the limits of his armor and body.
"Master! It's preparing to self-detonate!"
"Damn it! Activate all reserves—expand the wormhole!"
"Backup power engaged!"
"Compression complete!"
"Good. T0—get inside my armor. I'm going in."
"Master…"
"Thank you, T0. For everything."
"I'll always stay by your side."
"Luo Li—can you hear me?"
"I hear you!" Her voice trembled. "Bai Yue, please—"
"I'm sorry."
"Bai Yue, I'll be waiting for you!"
Zero smiled faintly. "Then I'll see you again."
He dove into the wormhole.
A blinding flash.
The wormhole imploded—shockwaves shattered nearby meteorites. Minutes later, silence returned.
"Zero! Bai Yue!"
***
"Master… wake up… please wake up!"
"Ugh… that hurts. Where are we? T0… are we still alive?"
"Yes, Master! We survived!"
"What? Didn't we perish with the Worm Mother?"
"I'm sorry, Master," T0 said softly. "At the last moment, I saved some reserve energy. When the wormhole collapsed, I separated you from the armor and redirected us through a spacetime tunnel. The Mother perished—but we were thrown into another world."
Zero blinked, then smiled faintly. "You did well, T0."
He reached out and patted her head.
"Um… Master…"
"What is it?"
"Could you… please put your clothes back on?"
"Clothes?" Zero looked down—and froze. His outfit had been torn to shreds, leaving only a thin, white underlayer.
"Ah—! T0, why didn't you tell me sooner?!"
He quickly retrieved a uniform from his nanospace and changed.
T0 covered her face, blushing furiously—but peeked through her fingers anyway.
Master's figure is amazing… No! What am I thinking?! I'm so embarrassed!