Zero certainly remembered: in the original story, Andromon had once been parasitized by a Black Gear and ended up fighting the Chosen Children before they eventually became allies.
But according to the original timeline, that incident should have happened shortly after the kids arrived in the Digital World. Judging from the current situation, Andromon shouldn't have been infected yet.
So Zero's plan had been to rush here, seek help, and at the same time warn Andromon about the Black Gears.
Given Andromon's power level, he must have been caught off guard in the original timeline. As long as he had prior knowledge and kept his guard up, a Black Gear shouldn't be able to parasitize him.
In short, Zero intended to play the timing.
But he never expected Devimon to move this quickly—fast enough to seize the Unmanned Mechanical Factory even before Zero's group arrived.
That made the situation significantly worse. Fortunately, they still had Rina's Digivice, which at least offered a countermeasure against the Gears.
All these thoughts flashed through Zero's mind as he completed his warp digivolution. As GeoGreymon, he rushed forward, unleashing a triple Mega Shot at the incoming Hagurumon.
Hagurumon weren't individually strong, but they made up for it with numbers. As machine-type Digimon, they were the "basic unit" of the Metal Empire—its most common component.
As their name implied, they were literal gears within that empire—fundamental parts of a vast mechanical civilization.
But now, each of these machine Digimon had a Black Gear embedded inside them. Unlike ordinary Digimon, machine-types could integrate a Black Gear directly into their bodies.
If other Digimon were merely "parasitized," machine-types were outright "assimilated"—the corruption far more invasive.
In Zero's memory, Hagurumon themselves could generate virus-laced gears to infect other Digimon. It wouldn't be surprising if this "virus gear" concept had inspired the design of the Black Gears.
Even as he recalled this, Zero's body didn't slow. The heatwave and shockwave from his triple fireballs shattered the Hagurumon formation. Zero dashed in, sweeping his steel-hard tail like a whip, sending a cluster of Hagurumon flying.
"Rina!"
Zero shouted instinctively. After half a month together, he and Rina had developed strong teamwork. She immediately knew what he meant.
"Got it!"
Rina raised her Digivice and scanned the fallen Hagurumon. A brilliant floodlight‑like beam erupted, causing the machines to screech in disorientation.
But unexpectedly—even at close range—the Black Gears inside them didn't fly out. Instead, arcs of electricity surged across their bodies, and several Hagurumon froze like malfunctioning equipment.
Even so, the corrupted gears within them continued spinning wildly. A few units shook off the paralysis and began struggling back to their feet. If not for the malfunction, they would have already charged again.
"Zero-kun! The scan… doesn't seem to work!"
Hearing Rina's voice, Zero's heart sank.
…So machine-types get affected far more severely? If that's the case, then is the Black Gear's design truly based on Metal Empire data? Damn—there's not enough information to confirm anything.
In that brief moment of distraction, several Hagurumon slipped past Zero and charged straight toward Rina and the Baby Digimon behind her.
At that critical moment, a burst of blue fire slammed into their path, knocking them back.
Since Hajime had asked to bring these Baby Digimon along, she naturally felt responsible for their safety.
That had been their formation on the road:
Zero handled the major battles and path-clearing.
Hajime protected the Baby Digimon.
Rina provided buffs and removed Black Gears.
Attack, guard, support—the three-person team was surprisingly well-balanced.
"Zero-kun! Leave the back line to me!"
Hajime fired another Blue Blaster to repel the attackers, then stepped firmly between the young ones and danger, her stance radiating unshakable resolve.
Zero roared, forcing away the Hagurumon trying to surround him. Seeing Hajime holding her ground, he felt a small measure of relief.
But before he could respond—
A sudden, electric shiver burst across his whole body, a shock so sharp it felt like every nerve had been pricked.
In that instant, Zero's breath stuttered, and his DigiCore trembled violently, almost out of control.
The sensation swept over him swiftly—a cold, invisible presence sliding against his skin like a chilling film.
"Not good!"
Zero reacted instantly, dodging to the side. Almost at that exact moment, from deep within the Mechanical Factory, a crescent-shaped wave of deep-blue energy erupted outward with a piercing roar.
Its speed was incredible. Zero had barely dodged when the energy arc sliced past his body. Had he moved even half a beat slower, it would have struck him dead-on.
So fast!
Even just grazing past him, the shock forced Zero back two steps. The energy wave then shot skyward, vanishing from sight.
Only after that sudden attack did Hajime and Rina react belatedly.
"Zero-kun!? What happened?!"
They tried to run to him—but Zero barked sharply:
"Don't come closer!"
They froze mid-step.
Zero fixed his gaze on the direction of the attack.
From the depths of the factory, a figure slowly emerged.
Its body gleamed with cold silver light—nearly eighty percent of its structure replaced with intricate machinery, with only faint traces of organic tissue remaining.
A first-generation cyborg-type Digimon of the Metal Empire's earliest era—its evolution line developed along the route of total mechanization.
Its modification data would later become foundational in the creation of MetalGreymon and even MetalSeadramon.
It was the very Digimon Zero had come to seek—
The guardian of the Unmanned Mechanical Factory.
An Ultimate-level Digimon—
—Andromon.