Back with Kouga.
Kouga slowly opened his eyes.
The first thing he saw was a metal-plated ceiling, cold and unfamiliar. Dim lights flickered above him, reflecting off reinforced steel panels.
Where am I…? he thought.
He tried to sit up—
And immediately felt resistance.
Something heavy pulled him back down.
Kouga looked down and saw thick, overengineered binding chains wrapped tightly around his body, locking him in place from legs to shoulders. Multiple restraint devices were layered over one another, each humming faintly with energy—as if whoever designed them had gone to extreme lengths to make sure he could neither move nor escape.
"…Overkill," Kouga muttered.
He shook his head once, then acted.
In a flash of light, Kouga transformed instantly into Kamen Rider Zero-One.
The bindings didn't even last a second.
With a sharp surge of power, the restraints shattered violently, fragments clattering across the floor as he stood up freely.
Kouga looked around the room. Bare metal walls. Reinforced flooring. And one massive sealed metal door at the front.
He raised his hand.
The Attache Calibur materialized in blade mode.
Without hesitation, Kouga slashed forward.
The door split cleanly in half, sparks flying as the metal peeled apart.
He stepped through.
Outside, Kouga found himself in what was clearly a containment block—rows of reinforced bays lining the corridor, each marked with identification numbers. Heavy security systems lined the walls.
"…So this is a prison," he concluded.
Suddenly—
A nearby door slid open.
Containment Bay 7.
Kouga immediately raised his Attache Calibur, ready for another fight.
But instead of an enemy—
He saw Himeko, standing there in her Scarlet Fusion battlesuit.
She looked exhausted. Scorched armor, visible damage, and the unmistakable posture of someone who had just survived a brutal fight.
"…Himeko?" Kouga lowered his blade slightly. "What happened to you? And where's Tesla?"
Himeko froze when she noticed him standing freely in the corridor.
Her eyes shifted past him—to Containment Bay 9, its door split wide open by a massive slash.
She let out a small, tired chuckle.
"…That answers that."
Then she looked back at Kouga and began explaining.
Otto had managed to create a specialized device designed to shut down Kouga's nervous system completely. Fu Hua and Rita had used it successfully, knocking him unconscious.
However—
What none of them expected was his body's automatic defense mechanism.
While unconscious, Kouga's body had reacted on instinct and forcefully transformed him into Kamen Rider Build — Black Hazard Form.
In that state, he had attacked everyone.
Tesla was knocked unconscious almost immediately.
Himeko, Fu Hua, and Rita had all been severely injured trying to hold him back—until Himeko finally managed to rip the Hazard Trigger off his belt, forcing the transformation to end.
"…I'm sorry," Kouga said quietly.
Himeko shook her head.
"It's fine," she replied. "You weren't in control."
She then continued.
Fu Hua had given her a Honkai-neutralizing serum—something that could temporarily delay the Honkai corruption spreading through her body. Fu Hua told her to find a safe place and use it immediately.
Himeko had refused.
"There was no way I was backing out," she said. "Theresa and the others are still fighting."
Kouga frowned.
"…Fu Hua attacked us. And now she's helping you?"
"Yeah," Himeko said. "Confusing, isn't it?"
She explained further.
Before disappearing, Fu Hua told her that if they truly wanted to help their friends, they would need to circle around the tower and reach the laboratories on the opposite side of the complex.
And just like that—
Fu Hua vanished without another word.
Kouga crossed his arms briefly, thinking.
"…So we're heading to that lab now?"
Himeko nodded.
"Exactly."
Kouga stepped forward, moving beside her.
"Then let's go."
Himeko and Kouga sprinted through the dim, metallic corridors of the facility.
Suddenly, Himeko raised a hand.
She stopped Kouga in his tracks and whispered urgently for him to hide.
They both ducked behind a stack of crates just as a group of surveillance drones glided past, their scanners sweeping the hallway with cold blue light.
Himeko whispered, "Drone patrols ... Can't risk detection. We'll go around carefully..."
After the drones passed, Himeko peeked out and pointed ahead.
She said, "That building over there should be the Guard Tower that Fu Hua mentioned... The labs should be around it... but it seems to be guarded..."
She exhaled slowly, eyes narrowing.
Then she muttered, "I need a weapon first..."
Before she could move, Kouga raised his hand.
With a flash of light, he summoned the Ryugeki Sword of Tyrannoranger from Zyuranger and handed it to her.
Himeko took the weapon and said, "Thanks."
The two of them moved forward, carefully weaving through the complex.
They avoided additional drone patrols, disabling laser security grids as they ran toward the laboratory sector.
As they moved, Himeko muttered uneasily, "I've heard of Helheim Labs before, but never expected to be here myself. This place sure creeps me out."
Ahead, several hostile units emerged—Asleikr Evoji and Asleikr Mystletainn–type drones.
Kouga, still in Kamen Rider Zero-One form, rushed in first, slashing through them with mechanical precision.
Himeko followed close behind, wielding the Ryugeki Sword with brutal efficiency, cutting down anything that slipped past him.
Within moments, the corridor was littered with sparking wreckage.
Himeko leaned forward, catching her breath.
She said, "Huff... huff... That's the last of them... "
The two of them continued onward until they reached a towering structure reinforced with thick armor plating.
Himeko looked up at it and said, "This is the Guard Tower... we need to go up."
Before either of them could move—
A faint sound echoed down the stairwell.
Both of them stiffened instantly.
Himeko raised her weapon and said cautiously, "...! Is anyone here?"
They stepped closer, moving slowly toward the elevator shaft.
The sound grew louder.
A strained voice echoed weakly:
"Hnngggh..."
Himeko whispered, "...the voice?"
The voice grew more frantic.
"Hnngh hnngh hngh hngh hnngggh!"
They rounded the corner.
And there—
They found Tesla.
She was tied tightly to a chair with layers of rope, her arms and legs completely immobilized. A complex, black-colored scarf had been wrapped around her mouth as a gag. She couldn't move at all—only wriggle helplessly.
Himeko stared at the ridiculous sight.
She had to bite her lip to stop herself from laughing.
Kouga just shook his head.
He walked over and carefully untied the scarf, removing the gag from Tesla's mouth.
The moment Kouga removed the gag, Tesla sucked in a sharp breath and immediately snapped,
"That evil maid! I don't want to see her ever again!"
Kouga blinked.
The last thing he remembered before blacking out was Rita Rossweisse standing over them, her scythe gleaming, and Tesla's mechs getting shredded.
So it really was her… he thought.
Himeko crossed her arms and asked,
"What did she do to you?"
Tesla scowled.
"...she gave me a world of humiliation."
Still furious about being tied up, Tesla shook violently in the chair.
Himeko stepped behind her to untie the ropes—and froze.
The bindings were arranged into a beautifully symmetrical, flawless knot.
It was so perfectly tied that Himeko hesitated.
…It almost felt wrong to undo it.
She muttered,
"...oh dear."
Tesla continued ranting,
"She kept apologizing while tying me up! "Ooooh... I'm so sorry, this might hurt..." What the hell!? Why would you tie me up if you were sorry at all!? The worst part was that she "kindly" applied some perfume on her hankie. That's not funny at all."
Kouga sighed and stepped forward.
"Yes yes, now let me untie you first."
He cut the ropes cleanly with the Attache Calibur.
Once Tesla was free, Himeko quickly explained everything that had happened earlier.
She finished with,
"...that's all I know."
Tesla clenched her fists.
"Now I'm really worried about mophead... we're not in a great shape either. I guess we can only head to the lab that somebody mentioned. We need to find a way to contact the Hyperion."
Himeko pressed the elevator control panel.
The system responded coldly:
"Error code 110327. Target not found. Access denied."
Himeko frowned.
"This elevator looks broken."
Tesla scoffed.
"It's just an elevator. I'll let you call me a moron if I can't fix this. Let's backtrack a bit. I need a terminal connected to the mainframe."
She knelt beside the panel and began working.
Then she glanced sideways.
"A question. What's up with that second rate sword?"
She pointed at the Ryugeki Sword.
Kouga stiffened.
"Second rate ?"
Himeko gestured at him.
"It's his sword."
Tesla shrugged and returned to her work.
"If the tiny gun of his could do that much damage the guess that sword isn't bad at all."
She pulled a small red device from her gauntlet and inserted it into the terminal.
The system chimed:
"Login device not found. You may need to install device driver first..."
Tesla typed rapidly.
After a few seconds—
"That's it. I've locked on to the target. Switching off this module will paralyze lab defenses.It will get the elevator moving, but we'll have to deal with some caged animals."
Himeko exhaled.
"Nothing I can do about that."
Tesla smirked.
"We can leave the mess to Schicksal."
She hit confirm.
"...access request verified. Commence system shut down."
The walls shook.
Doors burst open down the corridor.
Himeko spun around.
"The escaped test subjects are rushing in!"
Honkai beasts flooded the hall.
Kouga and Himeko charged forward.
Kouga cleaved through the front ranks with the Attache Calibur, sparks flying as corrupted armor split apart.
Himeko followed, her Ryugeki Sword carving brutal arcs through flesh and steel.
But more kept coming.
"Damn! There are too many of them!"
Tesla shouted from the console,
"Get back to the elevator!"
Himeko yelled back,
"we'll hold them off. Get yourself to safety !"
Suddenly—
The ceiling exploded.
A massive blue mech crashed down between them and the beasts.
Five times their height.
Its single glowing optic ignited.
Himeko staggered back.
"What's this?"
Tesla's voice tightened.
"Not good. We must have triggered the panic defense system! Careful. This one is dangerous."
The machine straightened.
Its giant metal sword ignited with pulsing blue energy.
The mech—Aesir Heimdall—raised its blade and brought it down.
Kouga shoved Himeko aside.
The sword smashed into the floor, detonating a shockwave that sent both of them skidding backward.
Heimdall stabbed its sword into the ground.
Energy surged outward in multiple vertical eruptions, ripping through the floor like explosive geysers.
Kouga rolled between the blasts.
Himeko vaulted over another, landing hard.
The mech roared and its blade elongated into a massive energy edge, sweeping in a horizontal arc.
Kouga blocked with the Attache Calibur.
The impact blasted him across the corridor wall.
He bounced off and flipped back to his feet.
Himeko charged from the flank, slashing into Heimdall's knee joint.
The blade bit deep.
The mech staggered.
It retaliated by backhanding her with its sword hilt.
She skidded across the floor and barely stopped herself.
Kouga dashed forward, leaping up Heimdall's arm.
He slashed across its visor.
The mech reeled and fired another ground-blast.
Kouga landed, skidding between explosions.
Himeko rushed in again, cutting power cables along its leg.
Heimdall's sword flared again into a long energy blade.
It swung wildly, shredding walls and support beams.
Kouga timed it.
He jumped straight into the arc.
He twisted mid-air.
Pulled the Attache Calibur overhead.
And brought it straight down in a single, perfect, vertical strike.
The blade cleaved through Heimdall's head unit, torso core, and power reactor in one clean line.
The mech froze.
Then split in half.
Both halves collapsed sideways and detonated in a thunderous explosion.
With the immediate threats dealt with, Himeko, Kouga, and Tesla rushed into the elevator and rode it straight to their destination.
The doors slid open.
Tesla bent over, hands on her knees, panting.
"Huff...huff... finally got rid of the riff raff... What is Schicksal researching in this place?"
Her eyes suddenly lit up as she spotted something mounted on the wall.
"Finally! A comm device! We'll be able to get in touch with mophead right now!"
She lunged at it like a predator going after prey.
The screen flickered.
Only static responded.
Tesla's face darkened.
"...Dammit!!"
She kicked a nearby metal container in frustration, then dropped to the floor, arms crossed.
Himeko walked over and looked down at her.
"You look terrible."
Tesla just humped in response.
Kouga glanced down the corridor.
"We should get going."
Himeko nodded.
"Let's push on. We don't seem to have a lot of options. Fu Hua said there's something in the lab that can save everybody. Perhaps it's something that we can use to defeat the Herrscher. Schicksal must have a fail-safe plan somewhere in case this thing got out of control. Perhaps that's where the answer lies."
Tesla pushed herself up.
"Alright."
She tapped her gauntlet.
"Just to be safe, I've set these coordinates to keep broadcasting an encrypted signal. ... I hope they could see that....but still, you know, right? That's it. Let's go."
The three of them moved deeper into the tower.
As they advanced, the sensation under their feet shifted.
Their steps grew lighter.
Tesla blinked and looked down.
"Whoah... Gravity has been reversed in this tower."
Himeko raised her gaze to the massive rings rotating above.
"...those rings have created a special grav field. I wonder what this massive installation is used for..."
They continued forward, navigating the strange inverted gravity.
Soon, multiple Asleikr Mystletainn mechas emerged from side corridors.
Kouga immediately drew the Attache Calibur and cut the first one down.
Himeko followed, cleaving another in half with the Ryugeki Sword.
Tesla ducked and weaved behind them, barely dodging incoming fire.
After a brutal skirmish, the last mech collapsed in a shower of sparks.
They reached another elevator platform.
Tesla leaned against the wall, breathing hard.
"Huff...Huff..."
Himeko looked at her, concerned.
"Can you still walk?"
Tesla straightened instantly.
"You gotta be joking. I'm fine!"
They pressed on.
At last, the massive reinforced doors of the Helheim Labs came into view.
Tesla crossed her arms and muttered,
"Plenty of guards here."
Himeko narrowed her eyes.
"We came to the right place. This lab is indeed hiding something."
Tesla smirked.
"Let's get things sorted out before we enter. We'll barge in, bash everything, and find the secrets of this place. Then we'll take the stuff and head back to the Hyperion. Finally, we'll pummel the Herrscher and send her packing. Mission accomplished."
Kouga quietly shook his head.
Himeko laughed lightly.
"Ha, ha, ha. I like your sense of humor, Dr. Tesla. Ready or not, here we go."
The three of them stepped forward—
And entered the Helheim Labs.
The moment the three of them stepped into the Helheim Lab, the sight before them left them frozen in place.
Tesla's eyes widened.
"What?"
An enormous array of highly advanced machining robots stretched across the entire floor.Conveyor belts, robotic arms, and towering fabrication units were all interconnected, forming a massive automated assembly line that hummed with quiet, relentless precision.
Himeko scanned the facility in disbelief.
"This looks more like a fab than a lab!"
Before any of them could process what they were seeing, a sudden alarm blared through the chamber.
Red warning lights flared to life.
Himeko tightened her grip on her sword.
"I guess here comes the welcome party. We'll mop these up and get to the bottom of this."
Asleikr Evoji units began emerging from maintenance bays and access corridors.
Kouga and Himeko surged forward, taking the lead.
Kouga slashed through the first wave with the Attache Calibur, while Himeko carved down anything that slipped past him with the Ryugeki Sword.
Metal shattered and sparks flew as they pushed deeper into the complex.
Soon, they reached an elevator platform.
The doors closed, and the elevator carried them downward into the depths of the facility.
As it descended, Kouga glanced at the glowing tubes lining the walls, watching streams of energy flow endlessly downward.
Energy is continuously flowing down the tubes. What is this lab hiding? he thought.
Himeko folded her arms, eyes narrowed.
"...this may not be a big place, but it's sure filled with secrets."
When the elevator doors opened again, Tesla hurried ahead, scanning the room.
She suddenly called out,
"I've found the lab control hub. Let me look through this. Gimme 10 minutes."
Himeko nodded.
"Alright."
Tesla didn't respond.
She was already fully immersed in the cascading data displayed across the screens.
Himeko found a quiet spot nearby and sat down, letting herself catch her breath.
She noticed Kouga standing off to the side, clearly lost in thought.
She looked up at him.
"What are you thinking Kouga ?"
Kouga answered calmly,
"I was just thinking on what form i currently have to prepare for the upcoming battle, that's all."
Himeko nodded in understanding.
Kouga continued thinking silently.
Sure, he could use the Super Sentai super forms now…But he still couldn't access his Kamen Rider final forms.The mecha were completely out of the question.
Tesla suddenly broke the silence.
"...Hey"
Her abrupt outburst made Kouga turn toward her.
Himeko also snapped back to attention.
Tesla scowled.
"What the hell is wrong with you? Kept shouting at both of you all this while. You two were completely phased out!"
Himeko blinked.
"...phased out ?"
Kouga bowed his head slightly.
"Sorry, was just checking on some of my power."
Tesla crossed her arms.
"Hmph. Must be all that fighting. They probably gave you shell shock or something....forget it. Get over here! I found something awesome."
Himeko and Kouga exchanged a look.
Then they both walked over to the computer Tesla was working on.