Muramasa replayed the moment of Amamiya Miyako's Zanpakutō materialization in his mind. The truth was, he hadn't fully entered Miyako's inner world. Instead, he had only brushed against it, nudging his thoughts ever so slightly—yet Miyako's Zanpakutō had forced itself into reality, draining a shocking amount of Muramasa's stored reiatsu in the process.
The gathered Captains and Lieutenants widened their eyes. None of them could hide their astonishment. Miyako's Zanpakutō… hadn't rebelled.
For many, this made no sense. Amamiya Miyako had only once revealed the full scope of his Shikai—and that had been in front of Aizen. To everyone else, his Zanpakutō's true nature was a mystery.
Renji and Rukia, who knew slightly more, only understood the power of the half-manifested Shikai—Shinya Zetsunen. But the true ability of his spirit—Kojin Zetsun—was far greater. One of its core powers, The Refuse, outright rejected any foreign reiatsu trying to invade Miyako's body. Even Aizen's Kyōka Suigetsu—the most perfect hypnosis—had no effect on him. Compared to that, Muramasa's influence was child's play.
"Tch… Miyako, this isn't fair," the black-haired Zanpakutō spirit—Zetsun—muttered bitterly, arms folded as if sulking. "If you force me into submission like this, you'll only ever have half my strength. And 'he' sure as hell won't like it."
"Half, huh?" Miyako's eyes sharpened as he smirked. "Half is more than enough. I never thought I could make both of you bow at once anyway."
That was the truth. What Amamiya Miyako was attempting right now wasn't some reckless stunt—this was Bankai training.
With his current reiatsu, there was no way he could fully materialize both halves of his Zanpakutō's spirit. But Muramasa's sudden intrusion gave him an opening. Instead of summoning both spirits, Miyako gambled on using Muramasa's ability and spiritual energy as a crutch to forcibly draw Zetsun into the world.
And judging from the black-haired spirit now standing before him, his gamble had paid off.
Miyako had activated his incomplete Shikai, Shinya Zetsunen, and then—by fusing his own reiatsu with Muramasa's ability—he successfully materialized Zetsun alone.
'Even if I manage to make Zetsun submit, this'll only count as a false Bankai. Not the real thing,' Miyako thought, exhaling slowly as the tension between them flared. 'But… even a false Bankai is still Bankai. And I'll take it, one step at a time.'
The sheer amount of reiatsu needed to fully materialize both spirits of his Zanpakutō was terrifying. Even Miyako knew rushing it would burn him alive. But this—this partial Bankai—was the first stone on that path.
Muramasa, meanwhile, remained eerily silent. Not only had he lost a chunk of his own energy to Miyako, but he still didn't understand the true nature of Miyako's Zanpakutō. That ignorance weighed heavily on him.
At last, Muramasa lifted his own sword, stabbing the blade deep into the ground. His voice carried across the battlefield, steady but heavy:
"Shinigami… your Zanpakutō are no longer yours. They've become my comrades. From this moment on, they will never again answer your call."
A sudden shockwave of pressure rippled outward.
And then, to everyone's horror, figures began to emerge from the shadows behind them.
Each one bore familiar features—too familiar to mistake. They were the spirits of their Zanpakutō.
"…No way…" Renji's eyes widened.
"The Zanpakutō… have all materialized?!"
...
After Muramasa and the other Zanpakutō had completely left, all eyes immediately shifted toward Amamiya Miyako and the strange figure standing beside him.
"Miyako-kun, what's going on? Why didn't your Zanpakutō betray you after it materialized?" Rukia asked, her voice filled with urgency.
"Uh… well…" Miyako scratched the back of his head awkwardly, his tone caught between honesty and hesitation. Should he reveal the true nature of his Shikai here? No… that secret was far too dangerous to expose so easily.
The truth was simple yet complicated—Miyako had borrowed Muramasa's ability while simultaneously using the hidden nature of his own Zanpakutō. This allowed him to become completely immune to Muramasa's enchantment.
"Miyako-kun… could it be that your Zanpakutō wasn't actually brought forth by Muramasa at all?" Ukitake's sharp eyes immediately caught the difference.
The Captain's gaze lingered on Zetsun, quietly comparing the aura between sword and master. The spiritual pressure radiating from him is almost identical to Miyako's own…
"My, my… Amamiya Miyako, you're something else," Shunsui Kyōraku spoke up as he strolled over with his usual easygoing smile, though his eyes carried clear surprise. "If I'm not mistaken… this looks like Bankai training, doesn't it?"
"Bankai?!" Everyone's voices rose together in collective shock.
"To borrow Muramasa's ability to materialize your Zanpakutō… all in order to force the conditions needed for Bankai training," Byakuya Kuchiki said coolly, his gaze sharp as steel. "Such recklessness. What would you have done if your Zanpakutō had turned against you?"
Miyako coughed lightly, bowing his head. "Captain Kuchiki is absolutely right. I… may have been too reckless." He chose to play along, rather than push the matter further.
The gathered Shinigami wanted to ask more, but before the situation could spiral, Captain Retsu Unohana's calm voice cut through the tension like silk.
"Enough. Captain Komamura and Captain Sasakibe are still gravely wounded, and many others across the Seireitei remain injured from this disturbance. The priority now is to treat the wounded and restore order. As for Vice Captain Amamiya's case… Captain Ukitake will look into it, and he may report back to us later."
As the eldest among them save for Genryūsai Yamamoto himself, Unohana's words carried undeniable weight. The other Captains and Lieutenants exchanged glances, then quietly dispersed to tend to their respective duties.
Miyako, Rukia, and Ukitake returned together toward the Thirteenth Division. Though it was already deep into the night, the barracks were still restless. Kiyone Kotetsu and Sentarō Kotsubaki rushed forward the moment their Captain appeared.
"Captain Ukitake! Has something happened in the Seireitei? We heard explosions everywhere just now!" Kiyone's voice was high with worry.
Since the Thirteenth Division's barracks were located on the outskirts, their squad had escaped direct damage, but the chaos had clearly reached their ears.
"And, um… who's this standing next to Vice Captain Amamiya?" Sentarō asked, blinking at the strange figure with suspicion.
Miyako hesitated, scratching his cheek. "Cough, cough… this is, uh… my close friend?" he said uncertainly.
Zetsun smirked, his voice smooth. "Miyako, don't downplay me like that. I'm something much more important than just a close friend."
The two Third Seats looked bewildered, but before their questions could spill further, Ukitake's gentle yet serious tone intervened.
"Kiyone, Sentarō… let us inside first. We have much to discuss."
******
The original author just decided to end the arc in such a manner. It was probably meant to be a side story since as you'll see later, he's not happy about following canon despite this being a fanfic.