When Pei Ran returned underground, she saw vague silhouettes through the smoke billowing from the front of the train.
It was Engineer Jiang and Aisha, emerging from the driver's cabin. Jiang crawled beneath the locomotive, while the old woman continued her vigorous train repairs with impressive energy.
Beside them was a small cart, loaded with tools and replacement parts. Aisha pointed to the cart, then gestured toward the door Pei Ran had earlier torn open—these had been scavenged from inside.
Jiang soon wriggled out from under the train, sitting down on the smoke-shrouded tracks, coughing a few times. She lowered her head, visibly caught in thought, as if unsure of something.
Aisha crouched beside her and began communicating again—serious, precise gestures, tapping her fingers in a specific pattern. Jiang responded the same way, one finger tap at a time.
Pei Ran watched closely. "They're using so many fingers… tapping different segments… I think these are letters."
W was observing too. "Looks like it."
If each segment of every finger represented a letter, tapping them in sequence could form phonetic spellings, and those in turn could string together whole sentences.
It worked—but painfully slowly. Saying even one sentence required a long series of precise touches.
Then Jiang turned to Pei Ran, pointed at her own head, and shook it, visibly frustrated.
Her expression said it all: the retrofitting of this train had happened decades ago. Some things, she simply couldn't recall anymore.
Pei Ran immediately asked in her mind, "W, do you have the schematics for the Nightsea-7 locomotive?"
"Of course," W replied. "One moment."
Pei Ran knew W would need to remove all written labels on the diagrams.
But "one moment" was practically instantaneous. A full set of diagrams arrived in her wristband interface almost immediately.
Pei Ran pulled them up, expanded the virtual screen, and moved it in front of Engineer Jiang.
They were blueprints—detailed structural diagrams of the Nightsea-7's front engine section, page after page.
Jiang froze, stunned by what she was seeing.
Her expression was pure disbelief: How is this even possible??
She flipped through them, eyes widening with each image.
The diagrams weren't just complete—they were more comprehensive than the ones she'd had access to during the original refit project. Every system, from core mechanicals to irrelevant subsystems, was meticulously catalogued.
She'd been struggling with repairs a moment ago, and now it felt like a treasure from the heavens had landed in her lap.
She glanced at Pei Ran again, deeply puzzled—Who was this girl, to have access to material like this?
Even Aisha's eyes had gone round. This time, she didn't even need to gesture. Pei Ran could tell she was thinking: This is insane. Where did you even get this??
Pei Ran thought to herself, Forget the Nightsea-7 schematics—if you asked for the plumbing layout of your bathroom, W could probably pull that up too.
Jiang kept flipping through the files. When she reached the last page, her hand stopped.
This one wasn't a flat blueprint. It was a full 3D rendering of the locomotive.
The model recreated the engine's internal structure with such precision that you could rotate it, zoom into components, and virtually explore every section. It was like holding a digital twin of the engine in her hands.
Back when Jiang had worked on the original retrofitting, tools like this hadn't even existed.
She looked up at Pei Ran again. Her astonishment could no longer be concealed.
This girl hadn't just "found" old schematics—what she had was even better than the originals.
Pei Ran saw her expression and understood immediately.
"W, you built this 3D model yourself?"
"Mhm," W replied casually. "I figured since I didn't have to create a repair plan, I'd just throw a model together using their data."
It had taken him less than a second.
With nothing else to do, he'd flexed a bit—for fun.
With the schematics in hand, Jiang's issues were quickly resolved.
She grabbed her tools and crawled back under the engine.
Not long after, she emerged again—this time, calm and confident—and motioned for Pei Ran and Aisha to follow her back into the driver's cabin.
Inside, the burnt-out wiring on the control panel had already been repaired.
Jiang took the driver's seat and flipped a row of switches one by one.
A low hum vibrated through the floor, accompanied by a subtle tremor.
Pei Ran and Aisha both looked to Jiang, who gave a small smile and a thumbs-up.
The train was fixed.
Aisha couldn't speak, but her excitement was palpable. She threw an arm around her grandmother and another around Pei Ran, hopping up and down in place.
Jiang let her hug for a moment, then gently pried her off and gestured toward Pei Ran: Time to move forward.
The smoke was getting thicker. The fire was growing. No time to waste—they had to go.
The train had a whistle, but no one was sure if using it would count as "making noise." It resembled a fire alarm in volume and tone, so it probably didn't—but why take the risk?
The smoke below had become so dense that the back of the train was no longer visible. Pei Ran didn't know if anyone else was still stranded on the platform.
She grabbed a wrench from the toolbox, leaned out the door, and banged it hard against the train's metal side.
CLANG—
CLANG—
CLANG—
The sound of metal striking metal echoed through the smoke-filled station.
She hoped that if anyone was still there, they would understand: the train was about to leave.
Jiang waited a moment, then pulled one lever down and nudged another forward.
Nightsea-7 began to move.
The train was quiet as it picked up speed, gradually leaving the terminal and entering the tunnel.
The entire city was in blackout. The tunnel was dark—but spaced at regular intervals were small emergency lights glowing in yellow. One by one, these points of dim light marked the way ahead. They weren't bright, but they told the people in the cab that there was still a path forward. It wasn't just endless, consuming darkness.
With the train in motion, Jiang leaned her elbows on the console and closed her eyes, rubbing her temples. She was old, and clearly exhausted after working nonstop.
Pei Ran tapped Aisha, pointing toward the rear cars, silently telling her to take Jiang to rest.
Aisha got the message instantly and helped her grandmother up.
Jiang stood, then gestured at the control levers. She was asking Pei Ran, Can you drive this thing?
Anyone else, and she would've been nearly certain the answer was no. These old trains weren't common knowledge anymore. But with Pei Ran… she couldn't be sure.
This girl had produced schematics even better than the originals. Anything was possible.
Pei Ran nodded confidently.
That was enough. Jiang looked relieved, then disappeared with Aisha into the passenger cars.
Pei Ran set down her backpack, placed the metallic sphere on the console, and took the driver's seat.
Even without W's guidance, she'd been watching closely enough to figure it out from Jiang's earlier movements.
She ran her hand over the levers and said to W, "Driving a train seems easy. No steering wheel. I'm guessing this one starts it, that one stops it. If you keep the speed steady, you basically don't need to do anything."
W, loyal advocate for train drivers, disagreed: "Sure, driving is simple. But conductors have plenty of other responsibilities—repairing breakdowns, handling emergencies, reading signals, following safety protocols. It's not as easy as you think."
Pei Ran looked ahead into the pitch-black tunnel. "At this point, are there even still signals or protocols left?"
Both she and W fell silent.
This was the end of the world. No more signals. No more rules.
Just a lonely, antique train, rumbling through the underground tunnels of a burning city, pressing forward.
After some distance, a spot of white light appeared ahead. It grew larger by the second.
The tunnel's exit was near.
That meant they were almost out of Nightsea's urban zone.
But the smoke followed them. Even with the doors shut, fumes seeped through every crack.
The light ahead grew brighter, the tunnel mouth forming a glowing arch.
Nightsea-7 sped forward—and shot out into the open.
Suddenly, everything was brighter—yet still engulfed in gray. The distant buildings were faint silhouettes. The fires in Nightsea had been too widespread—even the outskirts were cloaked in smoke. The twin rails ahead vanished into the haze.
A cold wind swept through. The smoke thinned slightly.
Suddenly, W shouted, "Pei Ran! Brake!!"
Pei Ran saw it too—a massive machine, like an excavator, lay directly across the tracks ahead, completely blocking the way.
She yanked the brake handle without hesitation.
The train screeched as it jolted into an emergency stop, wheels grinding against the rails with a sharp, grating scream.
Too close.
There wasn't enough time.
Whoever had placed that excavator on the tracks had done so with malicious precision—right at the tunnel's exit, where the light flared abruptly and thick smoke made visibility difficult. There was no time to react.
If they hit it, the train would derail. The front carriage would be destroyed first.
The green light inside Pei Ran—the one that could write—had been dormant this whole time. But now, sensing the danger, it stirred awake and began to tremble in her mind, ready to act.
Before it could, someone appeared beside her.
It was Aisha.
She had entered the control cabin, spotted the machine blocking the tracks, and stepped up beside Pei Ran. Eyes locked forward, she raised both hands in front of her chest with solemn focus.
Her ring fingers and pinkies crossed like braids. The middle fingers pointed straight ahead, index fingers curled around them, and thumbs pressed down over the top. The middle fingers pointed directly forward.
She had formed a mudra.
A speck of green light coalesced at the tips of Aisha's middle fingers. As the mudra shifted slightly—
Boom.
Pei Ran watched as the excavator blocking the tracks was lifted by a tremendous invisible force and hurled aside, completely clearing the way.
She turned her head toward Aisha in disbelief.
W spoke up. "Fusion."
Aisha was a fusion too.
The tracks ahead were now clear.
But then, out of the smoky distance, something strange came barreling down the rails toward them—clanking, clawing its way forward.
It looked like an excavator. But also not quite.
The thing was a grotesque patchwork of excavator parts haphazardly bolted together. The core of its body was a control cab, its feet were made of multiple shovels, and more shovels were raised like arms. It lurched forward in a chaotic, crablike gallop, arms flailing madly as it charged straight at the Night Sea No. 7.
W said, "It's CT122."
Pei Ran could see it now. This mechanical monstrosity wasn't some deranged fusion of man and machine—it had no signs of biological integration. At its core was a navy-blue sphere—the patrol bot from the Bureau of Public Order. Its serial number had been scratched off, and there were holes where it had been shot. The lower half of the ball was torn open and wired into the excavator parts.
It was that unkillable little bastard. W's stubborn cousin.
The clingy, relentless AI—CT122.
It had taken a bullet from W yesterday in the forest, yet somehow survived. Not only that—it had upgraded itself, stalked them to Night Sea, and concocted a clever trap to stop the train.
It was definitely getting smarter.
Its mission hadn't changed.
CT122 had only one goal: kill her—this L15-class high-threat individual. Relentlessly committed.
So committed, it didn't care at all that derailing the train might kill all the civilians onboard.
W zoomed in and said quickly, "See that transparent panel on its front? One corner still has the Bureau's insignia. My weapons can't pierce it."
The bot had been shot twice by W already. Now it had armored up with a shield. A big one, too—well-protected, but unable to fire while hiding behind it. No wonder it chose to block the tracks.
Aisha saw the mechanical beast charging at them. She hesitated, then formed another mudra.
But this time, the result was weaker. Her green-light attack only kicked up loose stones from the tracks beneath CT122, making it stumble for a moment.
She'd already used her green energy once—she couldn't sustain another full strike.
The green light in Pei Ran's mind was already in position.
Writing came with risk. But this time, the writing would be inside her own head. She had no other choice. She had to try.
Staring at CT122, Pei Ran focused, summoned the green light, and wrote two characters in her mind:
[Blast. Fly.]
They had to blast it off the rails. Only then could the Night Sea No. 7 move forward.
The air seemed to ripple with invisible force. CT122 faltered—and in the next second, its many limbs flailed as it was launched skyward.
It spun through the air, and then, as if torn apart by an invisible hand, its excavator components ripped loose, flying off in all directions.
"Blast" and "Fly" were executed perfectly.
Turns out, writing inside her mind was safe—Pei Ran remained unharmed.
And she made another discovery:
Like Aisha's ability, hers could target distant enemies without harming anything nearby. It even bypassed the train's windshield without a problem.
The navy-blue core of CT122 was hurled high into the sky—who knew where it landed. Pei Ran didn't care. She shoved the throttle forward.
Night Sea No. 7 surged ahead, leaving behind the shattered mechanical monster.
Aisha turned to Pei Ran in astonishment, momentarily forgetting her made-up hand signs. Her eyes were bright with wonder—
Like she had just found someone like her.
Pei Ran hadn't revealed her green light. But there was no one else it could have been. The mechanical beast had come straight down the tracks—no one in the rear cars could've seen it.
Only Pei Ran could have blown it to bits.
The view ahead cleared rapidly. The smoke thinned. They had reached the outskirts of the city.
The burning Night Sea faded behind them. The sides of the tracks held only scattered factories. The rail stretched forward, straight and endless.
Aisha let out a breath and began frantically tapping her fingers—
Then stopped. The sentence must've been too complex.
She pulled up a virtual screen from her wristband and opened the drawing board.
She carefully sketched a little stick figure.
The head was a circle with two dots for eyes, and its limbs stuck out like awkward branches.
W peeked over and commented, "I'm starting to believe the old saying: like attracts like."
Aisha's artistic skills were about on par with Pei Ran's. Equally terrible.
Then Aisha drew two vertical lines on either side of the stick figure. Beside the lines were stacked boxes, interrupted by mound-like bumps.
W frowned. "What is this supposed to be?"
Pei Ran said, "It's clearly a road, with collapsed buildings on either side. She's saying she walked down this road recently—some of the buildings had fallen. Your comprehension skills need work."
W: "…"
Sometimes the best tutor for a struggling student isn't the straight-A genius, but another student who just figured it out.
Same goes for bad art—bad artists understand each other.
The stick figure walked down the road. Then, from the sky, a green dot fell and entered its body.
The little figure twisted its stick-branch arms into a sign, and the stones on the road flew up.
Pei Ran understood: this was how Aisha gained her mudra-casting ability.
It was a destructive power—likely part of what W once called the "Entropy Class."
But maybe not. Pei Ran's own ability was classified under "Order," yet it could manifest as violent energy. It only looked like entropy.
Aisha stopped drawing and lifted her hands again, demonstrating mudras for Pei Ran—
Her fingers moved with practiced ease, flowing through intricate patterns.
She might've only recently acquired the green light, but she clearly hadn't just started learning the signs. Her fluency suggested she'd been playing with these hand signs for quite a while.
Pei Ran silently reached out and turned Aisha's arms—
Making sure the signs faced forward, toward the front of the train.
After all, when you're handling a weapon, you don't point the barrel at people.