Location: Floor 5 - The Abyssal Trench
Atmosphere: Crushing Darkness, Phosphorescent Dread
The warp gate dumped them not into water, but into a massive, glass-domed habitat located 20,000 leagues under the sea.
Outside the glass, bioluminescent Leviathans (imagine the Reaper Leviathan from Subnautica fused with the Sea Kings from One Piece) swam circles around their fragile bubble.
"Is that glass bulletproof?" Kazuma tapped the pane nervously.
Crkkkk.
A tiny hairline fracture appeared.
"DON'T TOUCH IT!" everyone screamed.
The Mission Brief
[OBJECTIVE: WAKE THE SLEEPING ONE]
[BOSS: CTHULHU (FUSED WITH GODZILLA)]
[RESTRICTION: Oxygen Tanks limited to 1 Hour.]
"Wake him?" Guts growled. "We should be killing it in its sleep."
"We can't," Kirito checked the HUD. "The exit portal is inside its mouth. We have to make it yawn."
Preparation
"I'm sitting this out," Luffy, Chopper, and Brook raised their hands. (Hammer weakness).
"We will be the cheering squad!"
Jin-Woo stepped forward. "I will handle the escort. My soldiers don't need air."
Arise.
From the metal floor shadows, a battalion of Naga shadow-warriors emerged. They hissed, adjusting their ethereal tridents.
Aqua walked to the airlock. She looked majestic. Her hagoromo floated in the zero-G water current.
"Finally," Aqua declared. "My domain! In water, I am the Supreme Goddess! I possess max stats! I cannot lose!"
"Don't jinx it," Kazuma muttered, strapping on a rusty SCUBA tank he stole from a locker.
The airlock cycled.
WHOOSH.
Cold water flooded the chamber.
Floor 5 began.
The Depths
Swimming in the abyss was terrifying. Even for the OP squad.
It was pitch black, lit only by Genos's headlights and Megumin's glowing staff (she refused to unequip it, even underwater).
"Something touched my leg!" Zenitsu gurgled through his regulator, clinging to Tanjiro.
"It's just seaweed, Zenitsu!"
"SEAWEED DOESN'T HAVE TEETH!"
It wasn't seaweed.
A swarm of Piranha-Creeper Vines lunged.
"Sacred High-Pressure Water Cutter!" Aqua shouted (via telepathy).
She swung her staff. A blade of pressurized water sliced the vines instantly.
"Whoa," Kazuma blinked. "She's... competent?"
Aqua grew smug. "I told you! Worship me! I am the queen of hyd—"
GLOMP.
A Giant Toad (Adapted for Deep Sea) swam out of the darkness and swallowed Aqua whole.
"AQUA!" Kazuma sighed. "Every time. Literally every time."
"Water Breathing: 12th Form - Undersea Rescue!" Tanjiro propelled himself forward, slicing the Toad's mouth open (gently) to free the slime-covered goddess.
"I hate frogs," Aqua wept bubbles.
The Leviathan Gate
They reached the trench floor.
In the center sat a temple made of green obsidian. The geometry was "Wrong". (Non-Euclidean angles that hurt to look at).
Sleeping on top of the temple was Godzillthulhu.
A mountain of scales, tentacles, and dorsal spines. It radiated nuclear heat that boiled the water around it.
"He's napping," Saitama floated near the creature's nose (which was the size of a city block). "He snores loud."
"We need to wake him," Midoriya prepared a Smash.
"Wait," Jin-Woo warned. "If he wakes up angry, he destroys the bubble city. We need to wake him gently."
"Gently?" Asta looked at his giant anti-magic sword. "I only know loud!"
"I have an idea," Jigglypuff (Pokemon) floated out of Misty's backpack.
"Jiggly?"
"No singing!" Kazuma stopped the balloon. "That puts him back to sleep!"
"Let me try," King (One Punch Man) swam forward. Or rather, he drifted uncontrollably because his buoyancy vest was too big.
He floated right in front of Cthulhu-Zilla's eye.
DOKI DOKI DOKI.
The King Engine resonated in the water like sonar.
PING. PING. PING.
The creature's eyelid fluttered.
It opened one eye.
A vertical, reptilian pupil focused on King.
It saw a man staring into its soul with vibrating intensity.
It felt the killing intent (actually panic heart rate).
The creature flinched.
"Does he know I'm awake?" the God thought. "Is he challenging me to a staring contest?"
Boss Battle Phase: The Alarm Clock
"NOW!" Kirito shouted. "Sonic attack!"
Brook (Soul King) leaped off a coral reef. He shredded his electric guitar (waterproof model).
"YO-HOHOHO! WAKE UP CALL! Party Music: Heavy Metal Soul!"
The blast of rock music hit the creature.
It roared. SKREEEEEE-ONK!
Atomic Breath began to charge in its throat. Blue light illuminated the abyss.
"Shields!" Naofumi summoned the Meteor Shield.
"I got this!" Vegeta swam forward. "Final Flash!"
Beam vs Beam underwater. The water turned into plasma.
Steam obscured everything.
"We can't see the portal!" Kazuma yelled. "Where is the mouth?!"
"I can smell it!" Tanjiro pointed. "It smells like bad fish and radiation!"
"Portal is open!" Genos targeted the gaping maw. "But it is closing! The creature is firing!"
"We need to prop it open!"
Luffy (inside the Bubble City, watching on screens) screamed: "Use the anchor!"
Not a literal anchor.
Iron Giant (Ready Player One / Fusion) dropped from the habitat.
Franky was piloting it.
"SUPER DOCKING!"
The robot jammed itself into Cthulhu-Zilla's mouth, holding the jaws open like a wedge.
"GO! GO! GO!" Franky yelled over comms. "It's slippery in here!"
The Exit
The team swam for the glowing vortex in the monster's throat.
Heat. Radiation. Bad breath.
"It's closing!"
The robot's arms were buckling.
"Serious Move: Serious Shove."
Saitama kicked the robot's back.
The robot (and Franky) shot deeper into the throat, wedging firmly.
"THANKS BALDY!" Franky yelled as he vanished into the portal.
Everyone swarmed in.
Kazuma grabbed Aqua (who was trying to purify the radiation and failing).
Jin-Woo recalled his shadows.
GULP.
The creature swallowed.
[FLOOR 5 CLEARED]
Intermission: The Belly of the Beast
They tumbled out onto a hard floor.
Dry. Stone.
Torches flickered on the walls.
"We... made it?" Usopp kissed the ground. "Solid earth! I love dirt!"
[WELCOME TO FLOOR 6]
[THE INFINITE DUNGEON]
[GENRE: D&D / ROGUELIKE]
"A dungeon?" Goblin Slayer's eye glinted red. "Good. caves. I know caves."
A Skeleton wearing a suit walked up to them.
Sans (Undertale).
"Heya. You've been busy, huh?"
"A skeleton!" Aqua raised her staff. "Turn Undead!"
"Whoa, chill lady," Sans sidestepped instantly. "I'm just the shopkeeper."
[SANS' SHOP]
Healing Potion: 500G
Bad Time: Free
Floor Map: 1 Soul.
"A soul?" Light Yagami (who had somehow survived Floor 5 inside a bubble) stepped forward.
"I have many souls." He opened his Death Note. "Which one do you want?"
Sans's eyes went dark.
"You're gonna have a bad time, kid."
Kazuma pushed Light away. "Ignore him! We'll take the map! Put it on my tab!"
Kazuma looked at the map.
It wasn't a dungeon.
It was a Labyrinth. And at the center...
[FINAL BOSS OF AINCRAD: KAYABA]
But Kayaba was waiting at Floor 100. They were on Floor 6.
"We skipped 94 floors?!" Kirito gasped. "The warp shortcut!"
"This is the Endgame," Vegeta cracked his knuckles. "Finally. No more games. Just violence."
A door opened ahead.
Massive. Golden.
Music swelled—One-Winged Angel played by an orchestra.
"That music," Cloud Strife (carrying the Buster Sword) stepped out from the crowd. "I know him. Sephiroth."
"Fused with who?" Kazuma asked, dreading the answer.
A figure descended on a single black wing. But he also had... tentacles? And a chaotic aura?
Sephiroth x Dhoulmagus x Aizen.
"Fusion Boss: The Angel of Despair."
He smiled.
"Shall I give you... despair?"
Saitama walked to the front.
"I'll take the combo meal with fries."