"Ardi!"
Rayleigh did not need to say anything else.
Ardi released Nejibana.
"Rankle the Seas and the Skies, Nejibana!"
The sword transformed into its massive trident, and a thin, carefully controlled sheet of water spread across the floor.
Ardi kept it away from Ais while directing the flow around the rest of the group and along the outer walls, giving the wild lightning an easier path than the adventurers standing in the chamber.
Bolts snapped into the water and raced away from them.
Ardi maintained the flow only until the discharge had passed, then dismissed most of it before the Enhanced Species could establish any prolonged spiritual connection to Nejibana.
The monster had seen another Zanpakutō ability, however, and immediately tried to turn toward Ardi.
Ais was already standing in its path.
"I'm your opponent."
Tempest erupted around her once more, and she accelerated beyond anything the creature had seen from her during the expedition.
Her first strike broke another spinal rod.
The second opened its shoulder.
Ais twisted beneath the creature's return slash and drove Gonryōmaru into the side of its abdomen, precisely between the clusters Asfi had identified.
The mouth along its flank opened around the blade, but Ais gave it no lightning to absorb and simply cut upward instead.
Gonryōmaru tore through the storage channel connecting the lower and upper clusters.
The Enhanced Species struck her with its free hand.
Ais crossed one arm against the blow but was still hurled across the chamber.
She twisted in midair, using Tempest to catch herself before she could hit the wall, and landed hard enough to skid several meters across the floor.
Blood ran from the corner of her mouth.
Tsubaki started forward, but Ais raised one hand without looking back.
"I'm fine."
Tsubaki checked herself. She understood the desire to finish one's own fight.
The Enhanced Species moved again, widening the wound Gonryōmaru had left through its abdomen.
Its regeneration was already trying to repair the damage, but the internal storage network had been divided into uneven sections, and lightning now leaked between the remaining rods in irregular pulses.
The creature raised its sword.
Ais got back to her feet, but something in her expression had changed.
Earlier in her life, a hit like that would only have driven her to attack harder, faster, and more directly.
She would have tried to overwhelm the monster before it could hurt her again.
That was exactly the Ais this creature had learned to imitate.
So she lowered Gonryōmaru and waited.
The Enhanced Species hesitated before attacking first, its thrust following her old pattern almost perfectly: a straight-line charge at maximum acceleration, everything committed to reaching the target before there was time to respond.
Ais moved aside by the smallest margin, allowing the blade to pass her shoulder.
She did not counter.
The monster was already prepared for that.
Instead, she let it finish the thrust and enter the recovery step it had copied from her.
Only then did Gonryōmaru move, severing another spinal rod before the creature could adjust.
It tried to turn, but Ais kicked the back of its knee and folded the leg beneath it.
She drove Gonryōmaru through its shoulder, then used Tempest to carry herself around the monster's body, wrenching the Zanpakutō through a long diagonal cut that opened three separate magic-stone clusters without leaving the blade in contact long enough for the mouths to drain her.
The Enhanced Species screamed as lightning began spilling from its wounds.
Ais landed behind it, and Gonryōmaru vibrated again, stronger than before.
She understood.
The creature still held an enormous amount of power, and most of it had originally come from Gonryōmaru.
Ais turned just as the Enhanced Species released everything it had stored, filling the chamber with a wall of blue-white lightning.
Rayleigh's hand moved toward Benihime, then stopped.
Ais had not asked for help.
She raised Gonryōmaru instead, allowing the first bolt to strike the blade, then the second and the third.
Rather than cutting through the attack or avoiding it, she let the stolen electricity gather around her Zanpakutō until so much lightning had wrapped itself around the steel that its original shape was difficult to make out.
Tempest pressed against the electrical force surrounding her, the wind preventing the charge from spreading through her body while Gonryōmaru drew more and more of it onto the blade.
The Enhanced Species continued emptying everything it had stored into her.
Ais accepted it.
The creature had spent the entire fight trying to steal Gonryōmaru's power, and now it was giving all of that power back at once.
Her hands tightened around the hilt as the gathered charge grew almost painful to look at.
The Enhanced Species opened every mouth across its body, ready to absorb whatever she sent back.
Ais never gave it the chance.
She vanished inside Tempest.
The creature turned too late, and Gonryōmaru drove through the damaged storage channel beneath its shoulder before emerging from the opposite side.
The mouths snapped toward the blade, but Ais had already forced it beyond their reach.
The lightning surrounding Gonryōmaru poured directly into the creature's damaged internal network, causing every remaining spinal rod to flare at once.
The Enhanced Species convulsed.
Ais ripped Gonryōmaru free, turned smoothly, and pointed the blade toward the monster. The electricity she had returned was already flowing through every part that mattered.
"Thunder Roar."
The chamber flashed white.
Four bolts crashed down around the Enhanced Species almost simultaneously, each striking one of the exposed metal growths and driving the stored current deeper into the ruined network.
Its absorption mouths opened uselessly. There was nothing left for them to intercept; the lightning was already inside.
Magic stones shattered beneath its ribs, another cluster burst near the shoulder, and the remaining spinal rods exploded from its back.
Ais ran through the smoke and drove Gonryōmaru into its chest.
The central magic stone broke beneath the point.
The Enhanced Species froze with its stolen sword still raised, but only for a moment before the weapon slipped from its hand and struck the floor.
Its body dissolved around Ais, leaving her standing where it had been as she breathed heavily and the last sparks of Gonryōmaru's lightning faded around her.
For several seconds, nobody said anything.
Ais lowered her gaze to the blade in her hand. Gonryōmaru answered with one long, satisfied vibration.
She could feel its presence more clearly now than she had before entering the Dungeon. There was no new name and no sudden second release.
Gonryōmaru simply felt closer than before.
Ais rested the flat of the blade against her palm.
"Did I do better?"
A faint spark jumped against her fingers, and her expression softened.
Rayleigh had watched the entire exchange from several meters away and knew better than to intrude on whatever passed between a wielder and her Zanpakutō.
Tsubaki had considerably less restraint.
"Well, Sword Princess, if Little Ume ever starts throwing my own fireballs back at me, I'm blaming you for proving this kind of nonsense works."
Ais looked at her.
"Tobiume would win."
Tsubaki stared at her for a moment before bursting into laughter.
Rayleigh decided it was probably better not to ask whether Ais meant Tobiume would defeat the imitation or Tsubaki herself.
Asfi walked over to what remained of the Enhanced Species and inspected the fragments of metal that had not dissolved with the rest of its body.
"It was more specialized than the earlier ones. Nearly its entire internal structure was designed around storing and discharging electricity. Whatever is coordinating these creatures isn't simply sending up whatever happens to be available anymore."
Lyra resealed Arachne.
"You think it made that specifically because Ais was here."
"Yes."
Asfi rose to her feet.
"It saw a problem and produced a response."
Rayleigh looked toward the lower passage.
That possibility had been bothering him ever since the signals began.
The creatures on these floors had been improving far too quickly for ordinary trial and error, and now they had confirmation that something below was deciding what the Enhanced Species should learn and sending specialized fighters back up to deal with specific threats.
Ardi resealed Nejibana and joined them.
"Then staying here only gives it more time to prepare another one."
"Exactly."
Rayleigh looked Ais over.
She had taken one solid hit and spent a considerable amount of Mind between Gonryōmaru and Tempest, but her breathing was already settling.
"You good to continue?"
Ais nodded.
"Yes."
...
They left the barricade chamber once they had confirmed that Finn's evacuation group had already cleared the upper junction.
With no wounded adventurers left to protect, the six of them descended more quickly through the passage beneath the training ground.
Rayleigh kept Benihime drawn as he led the way with Ais beside him, Gonryōmaru resealed but ready to be drawn again at a moment's notice.
Tsubaki and Asfi followed behind them, while Ardi and Lyra guarded the rear.
The deeper they went, the less the passage resembled the Dungeon they knew.
Monster corpses disappeared entirely, as did the repeated weapon marks they had been following. In their place, dark lines began to appear within the walls.
At first Rayleigh mistook them for mineral veins.
Then one of them moved.
Lyra stopped.
"Please tell me the wall did not just twitch."
Asfi crouched beside the nearest line without touching it.
The material was black, with a faint red sheen beneath its surface, and ran through the Dungeon stone in narrow strands no wider than a finger.
Another impact thudded through the wall.
The dark strand contracted in response. When a second impact followed, the contraction travelled farther down the passage.
Asfi's eyes sharpened.
"The signal is moving through these."
Rayleigh crouched beside her.
"Like nerves?"
"Functionally, perhaps. I wouldn't assume they're actually part of a nervous system yet."
She removed a small metal tool and lightly pressed its tip against the Dungeon stone beside the black strand.
Another impact came from somewhere below, and the tool vibrated in her hand.
Asfi withdrew it immediately.
"The vibration is strongest directly around the growth. Whatever these are, they're carrying the signal far more efficiently than the surrounding stone."
Tsubaki examined the material from above them.
"Dungeon growth?"
Rayleigh shook his head.
"The Dungeon is trying to close around it."
Once he knew what to look for, the signs became obvious.
Fresh pale stone had formed along both sides of the black strand, repeatedly pressing inward as though the Dungeon were trying to seal the foreign material beneath new layers of itself.
The dark growth had simply forced its way back through.
The Dungeon was repairing itself, while something else continued reopening the wound.
The humor disappeared from Lyra's face.
"So this really isn't the Dungeon suddenly deciding to become cleverer."
"No."
Rayleigh stood.
"This is something living inside it."
Ais rested a hand against Gonryōmaru. The pull on the Zanpakutō had become nearly constant.
"Close."
Nobody asked her how close.
They found the answer farther ahead, where the descending tunnel finally opened onto the thirty-ninth floor.
A broad natural chamber stretched beyond the entrance, but almost every wall had been overtaken by the same black growth.
Thick strands converged from dozens of directions before disappearing into a single opening on the opposite side of the chamber.
No monsters waited for them.
There were no stolen weapons or magic stones scattered across the floor, only the black veins and the steady vibration moving through them.
Three impacts travelled through the network, followed by the familiar pause and another five.
This time Rayleigh could actually see the strands contracting one after another as the signal crossed the chamber and disappeared into the passage ahead.
Asfi slowly removed her glasses, cleaned one lens, and put them back on.
"That is far too organized to be random."
Tsubaki drew Tobiume.
"Good. I was getting tired of chasing things that couldn't explain themselves."
Rayleigh looked toward the opening where every black strand disappeared.
The pull on his Zanpakutō was coming from directly beyond it.
Whatever had been consuming magic stones, collecting adventurers' techniques, directing the Enhanced Species, and producing specialized fighters had finally run out of floors to hide behind.
Beside him, Ais drew Gonryōmaru again, a quiet crackle passing along the blade.
Rayleigh stepped toward the opening.
"Let's see what has been teaching them."
Something on the other side of the passage struck the wall once, and the entire network answered.