Ryuga led Kamen Rider Build down the damp tunnel he had once escaped through. They ran in silence, their feet disturbing the inch of water covering the floor of the tunnel, which was the only sound to be heard for quite some time.
After traveling who knows how many miles underground, the pair reached a set of stairs leading into a mechanical room housing many boilers and ductwork. Armed guards patrolled along the steel scaffolding, with protective railings that acted as walkways.
Ryuga peered deep into the room and spotted what he had been looking for.
"The lab is over there," he quietly said to Build behind him; both were crouched behind a small brick partition that kept them just out of view of the helmet-wearing gunmen.
They had a strange appearance: sleek helmets with gas filtration attachments, what looked like armored formal suits, and combat boots... quite the look.
Build cracked his knuckles and motioned toward the lab with a tilt of his head.
"Go."
Ryuga nodded and stood up, leaping over the partition while Build slotted two different bottles into his driver, one purple and one blue.
NINJA!
TANK!
A hologram of a ninja star and a tank appeared side by side in front of the bottles as the essence in them was dumped into the driver.
"Hey!"
Ryuga ran out in front of the guards, waving his hands and getting their attention with his yell.
"What are you losers up to?!"
Ryuga raised both of his hands, displaying his middle fingers on either side, prompting the guards to start raising their weapons and advancing toward him.
Before they could even think about aiming at Ryuga, however, a blue and purple streak came flashing toward them from the side.
Living up to the style of one of his ninja bottle, Build flipped through the air silently, slashing at the first guard, who only noticed him at the last moment.
Whack!
The hilt of Build's Drill Crusher crashed into his helmet and dropped him onto the floor.
Without wasting any time, Build flipped the second weapon he was carrying, the Four-Panel Sword, into a backward grip and proceeded to dance between the remainder of the armed men, slashing their weapons into pieces and knocking them out one by one before they could make a sound or raise the alarm.
Ryuga just stood there watching the show, laughing.
"Come on, let's go!" Ryuga started heading toward the lab, which was less than twenty feet away now.
"Agggghhhh! Help me! Someone please help!"
Both looked at each other after hearing a scream and panicked plea for help from just ahead; they rushed forward and passed a brown chair before staring down at a very familiar sight.
Men in white lab coats and biohazard suits, wearing gas masks, were shoving a man into a glass box neither Build nor Ryuga could ever forget.
The man struggled and fought back violently, trying to avoid being put into the box with all his strength.
The test subject had been fighting so hard and screaming so loud that none of the lab rats had noticed Ryuga or Kamen Rider Build approaching at all.
Until they were right on top of them.
One scientist finally noticed the two uninvited figures looming overhead. "What the...?!"
Build undid his transformation, and Ryuga stood stock still with a crazy look in his wide-open eyes.
The scientists all started to scramble, and Ryuga rushed forward with a yell.
Sento stood with his belt still on and suddenly felt weak in the knees; he reached out to the nearby railing for support while staring at the lab, drawing in quick, deep breaths. His dreams and the view in front of him were melding into one, recovering a small piece of his memory.
"I was here..." he said while trying to calm down his breathing.
Meanwhile, Ryuga was thrashing about in the middle of the rogue scientists. One hung around Ryuga's neck, not slowing him down at all as he pushed them around.
"You assholes remember me?!" he shouted into one of their masked faces.
He threw the man on his back over his head as if he weighed nothing, kicking him in the ribs when he hit the ground. The others watched the downed man holding his chest, wriggling in pain on the floor, and turned tail to run away from the wrathful Ryuga.
Ryuga's eyebrows shot up at the sight of them all retreating and gave chase while shouting, "Who gave Nabeshima the orders?! Tell me, ya trash!"
He caught up with one lab coat quickly and grabbed his shoulder, spinning him around. Ryuga grasped the other shoulder with his spare hand and started shaking the masked scientist violently; then proceeded to smash him back and forth against a nearby rack holding test tubes and instruments, knocking them to the floor.
"Who framed me?! Talk, you bastard!" Ryuga yelled so hard that spit flew out of his mouth and landed on the man's goggles.
The test subject who had been struggling beforehand picked himself up off the floor from where he had been dumped in the mad melee earlier. He started to run past the other test subjects who were strapped to their hospital beds, toward the stairs that led up and away to possible freedom.
Zzzzzap!
A blast of purple, pink, and white energy landed on the fleeing test subject as he neared the base of the stairs.
"Arrrrgghh!" The expression on his face changed from hopeful, to shocked and horrified as he fell to the floor, twitching for a few moments before stopping moving entirely.
Blood Stalk stood at the top of the stairs and held a specialized energy weapon in his hands nonchalantly. Smoke was still pouring out of the business end of the gun.
A squadron of reprogrammed Guardians followed behind the pink and teal Rider.
"Stop shouting!"
Blood Stalk yelled loudly, causing the room to fall silent. Even Ryuga slowed down mid-interrogation to turn and give Blood Stalk a death stare.
The evil Rider nodded his head in approval of the quiet that had fallen. He started to walk toward the scientists and Ryuga and said mockingly, "When you're so loud, it's rude to our guests."
Ryuga tossed the man he had been holding by the collar to the side and turned to face Blood Stalk. He walked toward the man in pink armor and asked quietly, "Who the hell are you? Pink bastard..."
Blood Stalk ignored the question, held his hand up to signal the Guardians to stay where they were and started walking casually to meet Ryuga, his long energy gun swinging loosely in his hand as he strolled forward.
"Don't move and behave yourself..." Blood Stalk lifted the gun for a few seconds, pointing it at Ryuga's head threateningly before dropping it back down beside his hip. He sneered and tilted his head.
"...I'd hate to be forced to kill an important specimen."
Blood Stalk stopped walking when he was around ten feet away from Ryuga. He let his gun hang and stood with one hand on his hip. You couldn't see behind his helmet, but you could just tell from his body posture how much he looked down on the man in front of him.
Ryuga narrowed his eyes at the man. "Specimen?"
"Screw you!" He launched himself toward Blood Stalk in a fit of rage.
Ryuga tried to throw a punch at him, but his arm was caught easily.
"I warned you..." Blood Stalk shook his head while easily restraining the struggling Ryuga. A small tendril snaked out from his wrist armor and pierced Ryuga's neck, causing dark black spiderwebs of poisoned blood vessels to appear.
He pushed Ryuga back and watched his handiwork spread.
"Arrrrrgghh!" Ryuga screamed out in pain. It felt like white-hot, liquid metal had been pumped into his body.
Sento was shocked out of his stupor. "Banjo!" he called out to his staggering friend while rushing forward.
Blood Stalk stood in place while Ryuga stumbled and fell into Sento's arms.
"Hey... Hey!" Sento wasn't sure what to do, staring at Ryuga in horror as the man's face started to turn blue.
"...Poison..." Sento looked Ryuga up and down, watching as his skin took on a nasty hue from top to bottom.
Ryuga looked terrified while clutching frantically at Sento's chest and shirt. He was in terrible pain, couldn't breathe, his vision was blurring, and his eyes were now bloodshot.
Ryuga gasped one more time for air with no results, and his red eyes rolled into the back of his head. He went limp and slipped through Sento's hands, hitting the ground and remaining still.
Sento immediately started shaking his friend, trying to wake him up.
"Hey, Banjo! Come on, Ryuga!.. Banjo!.. Banjooooo!"
Blood Stalk shook his head in disappointment and slowly sauntered forward while chuckling, "Tsk tsk, what a shame..." He crouched down to look at Ryuga's pitiful state when he was around five feet away from Sento and the unresponsive boxer.
He shrugged his shoulders in dismissal and laughed. "...Haha... Oh well. We've got another special specimen after all. All good."
Sento's eyes darted back and forth after hearing Blood Stalk's taunting tone. "What do you mean by that?"
Blood Stalk tilted his head to the left dramatically while giving Sento a look. It was hidden behind the helmet, but you could just tell he meant, "You haven't figured it out yet?! Noob!" He finally spoke after letting at least five seconds go by.
"Your body has been exposed to the same amounts of Nebula Gas that creates Smash."