Author's Note: Please enjoy!

Chapter 4

Emu and Parado arrived to find Sento and Takeru waiting outside for them.

Takeru greeted them each with a warm handshake and Sento waved casually, preferring not to get too close.

"Thank you for coming on such short notice," Takeru said.

Emu patted him on the back. "Anything for a fellow Rider."

Parado stayed out of reach and his silent stare had Emu sigh.

"So you said we were using a portal?"

Sento's face lit up and he pulled a small handheld remote from his coat.

"This child is the World Tunnel. It uses a similar type of energy to the Gamma Portals but ensures that the rift is only open while the user holds the button. Of course, it takes some fine calibration to make sure that it opens at the right spot but the calculations aren't that hard. It's absolutely genius."

He flicked his fringe back from his brow with an almighty smirk.

"And you're sure it's safe?" Parado finally spoke up, eyeing the device and Build warily.

Sento raised an eyebrow.

"I used it to come here. Besides, it's much safer than the Enigma machine you traveled through."

"We shouldn't keep the patients waiting any longer, then," Emu said.

Takeru nodded and gathered some of Emu's medical supplies.

"Watch out!" Parado yelled.

The Riders barely had a chance to react as a flaming haze descended upon them.

Parado threw himself at Emu, tackling him to the ground as Takeru rolled to a crouch and activated his Rider Belt.

Sento, separated from the others, had bottles in one hand and the other slinging his belt around his waist as the smoke cleared.

In the centre of a burning ring on the ground stood a Kamen Rider.

Or at least it looked like a Kamen Rider.

It was certainly no Smash, Ganma, or Bugster. The armour was sleek and humanoid, made entirely of black and gold. A full helmet covered the wearer's face, luminescent eyes slanted and emotionless.

"Does anyone know this guy?" Takeru asked.

"This is your world," Sento countered.

Emu and Parado shook their heads in unison.

"I suspect he isn't here to help, considering that attack," Emu said.

Takeru held out his arm when Emu equipped his belt.

"We've been wrong about intentions before. Just give me a second to-"

The new Rider launched itself at Takeru. Surprised, he wheeled back, defending against the first kick and punch with clenched teeth as the blows did damage without his armour.

"Rabbit! Tank!"

A fully transformed Build jumped into the fray, distracting their new adversary with his own barrage of kicks.

Takeru got clear and began his own transformation.

"Bachiri Minna. Ore Kaigan: Ghost! Let's go, Kakujo, G-G-Go- Ghost!"

Emu loaded his Mighty Brothers X Gashat.

"Gashat! Let's Game! Metcha Game! Mutcha Game! What's your name?! I'm a Kamen Rider!"

Emu and Parado transformed as one into their separate halves and ran to help Build.

The strange Rider pulled at a device on his hip and there was a burst of light.

All four Riders shielded their eyes and ducked out of instinct. As the dots cleared from their eyes, they came face to face with six copies of the unknown Rider.

Build, Ghost, and Ex-Aid exchanged glances.

This was going to be trouble.

They braced themselves, standing back to back together as the black and gold Riders advanced.

The unknown Riders immediately went to divide and conquer. They threw a barrage of long range attacks, knocking all four Riders off of their feet. The Mighty Brothers struggled back upright to find themselves confronted by two of the unknown Riders. A punch here, a bruising blow to the back and Emu's side was pushed back. Parado followed, pulling Emu to his feet and using the motion to launch a counterattack. The blow glanced off and the unknown Riders followed up with a sharp fire attack that ate at Ex-Aid's armour.

Ghost ran past, two of his own enemies on his tail. They maintained their distance, preferring to use hissatsu attacks than to get in close quarters.

Takeru loaded a new eyecon, pulling his belt to activate the change.

"Kaigain: Nobunaga!"

He fired as soon as his pistols came into existence, trying to target one in particular so he could at least lessen the spread of his focus. His shots were accurate but not powerful enough. He reloaded but the second unknown Rider kicked the gun from his hand.

Then both of them were attacking, joining together for one large hissatsu attack. Takeru braced as the ball of flame hurtled toward him and he staggered as he took he hit. His transformation came undone instantly but he righted himself and loaded a new eyecon, re-transforming to Ghost and rushing towards his enemies once more.

Build saw Ghost's transformation come undone but even his initial instinct to defend was quashed by the intrusion of his two adversaries. They stayed close, kicking, punching, and not giving Sento any chance to power up a hissatsu attack or change his bottles. Locked in his basic Rabbit Tank form, he found himself doing little more than protecting himself.

This couldn't last. In a battle of endurance, two would always beat one and Build didn't have the time to wait to see if they would give him a better opening. He had to get some space and then regroup with the others.

He added some extra power to Tank's leg for a sweeping kick and was gratified to see both his enemies jump back.

Sento took the chance and ran, heading to the outdoor Shrine.

"Ex-Aid!" He shouted as he bolted past the Mighty Brothers. He saw them both look out of the corner of his eye but didn't stop to check they would follow.

He dived behind the donation box at the Shrine and fumbled for new bottles.

An explosion threw him to one side and he gasped as pain exploded in his side.

He groaned and tried to shift but something was pinning him down. His transformation was holding but just barely and his fingers tightened around his new bottles as a shadow fell over him.

""Build! Are you ok?!" Ex-Aid bent beside him and between the two Mighty Brothers, they managed to lift the fallen beam from Sento.

Sento winced as he sat but accepted the hand offered by one of the brothers: he wasn't quite sure which one.

"Behind you!" he rasped.

The brothers turned to find four enemies upon them. They braced and defended as Build transformed behind them.

"Tank! Tank!"

Build rejoined the fight but it was complete chaos. He could barely move and assaults seemed to be coming from everywhere. Ex-Aid didn't seem to be doing much better and they were knocked back into the wall of the Shrine.

Build's transformation finally came undone and he gasped for breath as the Mighty Brothers struggled to rise.

The four unknown Riders were powering up a nasty looking attack.

Sento looked around him. They had to get out of here. The remote!

He rolled over and reached into his coat but the device wasn't there. He rolled back onto his stomach.

He must have dropped it. Where was it? There!

The device had spun under the donation box and was out of Sento's reach.

He dragged himself towards the fallen invention but quickly found himself pinned by Ex-Aid.

"Watch out!" The Mighty Brothers yelled in unison.

Sento glanced behind them to see the attack was unleashed and hurtling toward them. He wasn't going to get the remote in time. He closed his eyes and waited for the moment of impact.

It didn't come.

Eyes snapping open wide, Sento looked in horror to see Ghost's transformation come undone. Smoke rose from Takeru's body as he fell.

"Ghost!" One of the Mighty Brothers yelled.

Sento spun and continued his crawl toward the fallen remote as Ex-Aid ran to help Ghost.

Another explosion charred his arm as he reached for the device but his fingers closed around hard plastic. He retrieved the device as the Mighty Brothers dragged Takeru's limp form back.

Sento took one look at the pale face and bloody forehead and knew Ghost would not be waking up anytime soon.

"We can't win!" he shouted to Ex-Aid. "We need to retreat!"

There was no reply from Ex-Aid as all six of the unknown Riders attacked. The Mighty Brothers valiantly held the line, braced against the attacks as Sento activated the portal.

He heaved Takeru into a sitting position and rolled him through the horizon.

The unknown Riders were starting to overpower Ex-Aid.

"Ex-Aid! Now!" Build yelled.

One of the Mighty Brothers looked at him.

"Emu! Go!" he pushed the other Mighty Brother away from the fight and took on all six attackers by himself.

The other Mighty Brother – Emu, Sento assumed – shook his head and tried to re-enter the fight.

"Go, Build!" Parado yelled, pushing Emu away again.

Sento gritted his teeth and transformed into his basic form again. He struggled to his feet, wrapping his arms around Emu's waist and pulling him to the portal. Emu fought him.

"No! We can't leave!"

Sento took one more look at the remaining Mighty Brother and nodded once before leaping into the portal and pulling Emu through too.

"No!"

Emu reached out his hand, still resisting.

"Parado!"