After splitting from Ichigo and the others, Rukia had been led by a masked figure into one of the towering spires of Las Noches. Inside the sterile, white chamber, her guide finally removed his mask.
"Kaien… Vice-Captain?!" Rukia's breath hitched, her eyes wide with shock.
The face revealed was unmistakably that of Shiba Kaien, her former mentor and the source of one of her deepest regrets.
"Oh, Rukia. It's been a while. The sun outside gives me such a headache. Only in here can I show my true face," Aaroniero Arruruerie said, perfectly mimicking Kaien's warm, reassuring tone with a sigh of feigned relief.
"What… what is this? What do you mean, 'outside'?" Confusion and a desperate, fragile hope warred within her.
"It's like this. Everything under that false sky is under Aizen's surveillance. Only within these walls can I speak to you freely." The lie rolled off his tongue with practiced ease.
"Aizen's surveillance?" Rukia's instinctive trust in that face made her want to believe, but caution held her back. "Vice-Captain Kaien, why? Why are you here? What is happening…?"
"I know, I know. I'll explain everything." Aaroniero continued the deception, weaving a tale that made Rukia's heart ache with the possibility that her beloved senior had survived.
Seeing that familiar smile, Rukia wanted to believe. But a sliver of doubt remained.
"By the way, Rukia," Aaroniero shifted, his mimicry flawless. "Did you come to Hueco Mundo for… that?" He pointed a thumb upward.
Rukia's gaze followed. Suspended in mid-air, glowing with an inner blue-black light, was a perfect orb.
"The Hōgyoku?!" she gasped. She had witnessed the artifact being extracted from her own body by Amamiya. According to him, Urahara had ultimately secured it. To see another here…
"So you recognize it. Then, Rukia… are you here to steal Aizen's Hōgyoku?" Aaroniero pressed, keeping Aizen's orders foremost. Uncovering their true goal, or locating the other Hōgyoku, would be a great service.
"No… We came to rescue Inoue Orihime and her friend. But for Aizen to leave the Hōgyoku here…" She murmured, her eyes locked on the glowing sphere. A fierce determination sparked within her. "No, I can't let this chance pass. Vice-Captain Kaien, please, let me take it! Taking the Hōgyoku is the surest way to stop Aizen!"
She leapt upward, hand outstretched toward the floating prize.
Below her, Aaroniero bowed his head. "Is that so… What a pity." Learning she was not the Hōgyoku's bearer was a disappointment. The charade was over.
As Rukia reached for the orb, Aaroniero moved. His borrowed Zanpakutō flashed from its sheath as he jumped, his blade slicing toward her outstretched arm.
Rukia sensed the attack but reacted a fraction too slowly. The edge caught her forearm, opening a thin, bleeding line. She landed, clutching the wound. "Why…? Vice-Captain Kaien, have you betrayed us?!"
"How could I, Rukia? I merely wished to test your skills. To see my former subordinate grown so strong… it eases my heart!" he proclaimed with false warmth.
Rukia stared, the dissonance growing. The face, the voice, the shared history… yet something was profoundly wrong.
Outside the tower, Amamiya Miyako, having tracked Rukia's spiritual pressure, assessed the situation. 'Aaroniero Arruruerie… The imposter.'
Reaching into his cloak, he drew out his Quincy Cross. Using Quincy power here would misdirect any observers; they would assume it was Uryū Ishida. He could finally weaponize this long-hidden facet of himself.
He summoned a Heilig Bogen. The Reishi in Hueco Mundo was so dense that the bow that formed in his hand was massive, far larger than intended.
'Well… this will do.' He aimed the colossal spiritual bow at the tower's apex. Instead of a single arrow, he willed the gathered energy to fracture.
"Go… Licht Regen." (Rain of Light)
The fired arrow disintegrated into a torrent of hundreds of smaller, lethal beams of concentrated Reishi. They screamed through the air, impacting the upper structure of the tower with devastating force. Stone and plaster exploded inward.
Inside, both Rukia and Aaroniero were shaken by the sudden bombardment. Then, with a final crash, the entire top of the tower was sheared away. Blinding, unfiltered sunlight flooded the chamber.
Aaroniero Arruruerie let out a piercing, agonized shriek. The flesh above his neck—the stolen visage of Shiba Kaien—began to smoke, bubble, and dissolve under the sun's rays.
Rukia watched in horrified fascination as the familiar face melted away.
"Who are you?! You're not Vice-Captain Kaien!" she demanded, her initial shock hardening into icy clarity. The mysterious attack had been a blessing. The lie about "avoiding Aizen's surveillance" had just been a ruse to hide from the light.
"Damn it! Who dares?!" the creature roared. From the fluid-filled tank that was now its true head, two bizarre, grotesque faces surfaced, their voices overlapping. "You've discovered us, Rukia."
"We are the Novena Espada. Aaroniero Arruruerie."
"Is that so…" To her own surprise, Rukia felt a wave of relief wash over her, followed by a cold, focused calm. "If you're not him… then I have nothing holding me back."
She raised her Zanpakutō. "Dance, Sode no Shirayuki!"
The blade transformed into its elegant, pure white Shikai form.
"Sode no Shirayuki? Useless, Rukia! I've seen it all in Kaien's memories! He helped you achieve Shikai, didn't he? First Dance: White Moon, Next Dance: White Ripple, Third Dance: White Sword! I know them all!" Aaroniero cackled, his twin voices grating.
"Really? Then perhaps you should look at your feet." Rukia's voice was frost itself.
Aaroniero glanced down. A layer of glistening, impossibly cold ice had silently encased his feet, anchoring him to the floor.
"What?! First Dance?! When?!"
"Did you think," Rukia said, her tone sharper than any blade, "that after Vice-Captain Kaien's death, the Thirteenth Division stood still? That I made no progress?" She gripped Sode no Shirayuki's hilt with both hands, leveling the tip at him. "Let me tell you. The Thirteenth Division has a new Vice-Captain. His name is Amamiya Miyako."
A strange change came over her. The blood from the cut on her arm ceased to flow, flash-frozen over the wound. A delicate, deadly layer of white frost began to creep across her skin. Her voice flattened, losing all emotion, as if her very life force was being suppressed.
"And all these years… Miyako and I haven't been idle."
"Impossible!" Aaroniero struggled, but the ice holding him was far colder, far stronger than any memory of Rukia's power suggested.
"With Miyako's guidance… I began to understand the true nature of my Sode no Shirayuki." In a blur of motion, she vanished from her spot.
A line of crimson appeared across Aaroniero's torso. Before the blood could spray, it froze solid, the wound instantly sealed beneath a layer of glacial ice.
"GYAAAAAH! What is this?! Kaien's memories have nothing like this!" He screamed in genuine panic and pain. The cold wasn't just external; it felt like it was freezing his very spirit.
Rukia reappeared, her expression serene and utterly merciless. "This… is Sode no Shirayuki's true power." Under Amamiya's relentless drills on battlefield secrecy, she knew never to reveal her trump card. She offered no explanation, only the silent, deadly promise of the next strike. The dance of the white sword had evolved into something far more absolute.