The sun had barely dipped below the horizon when Amamiya Miyako and Rukia returned to the Thirteenth Division barracks after a long day of training. Just as they arrived, they were met by their Captain, Ukitake Jūshirō.
"Miyako, Rukia, perfect timing," Ukitake said gently. "The Captain-Commander is summoning us."
"The Captain-Commander? At this hour?" Rukia blinked, confusion written across her face.
Miyako tilted his head, narrowing his eyes. Something about this didn't feel right. Still, he clenched his fist slightly at his side. No matter what it is, I have absolute confidence in my Zanpakutō. This incident… might even prove useful.
"I'm not sure of the details myself," Ukitake admitted. "But if Captain-Commander Genryūsai is summoning us, it must be serious. Let's go."
He led Miyako and Rukia swiftly toward the designated hall. When they arrived, nearly the entire Gotei 13 was already assembled—Captains, Vice-Captains, and a handful of others.
"Shunsui?" Ukitake called in surprise when he saw his old friend. "You and your Vice-Captain were summoned too?"
Shunsui Kyoraku tipped his hat lazily, though his eyes were sharp. "Yeah. Though I can't imagine why old man Yama would call not just Captains and Vice-Captains…" His gaze shifted briefly toward Rukia, and then to Ikkaku Madarame and Yumichika Ayasegawa of the Eleventh Division. His brows furrowed slightly.
Before anyone could say more, a figure stumbled into view.
"Chōjirō-san!"
It was Chōjirō Sasakibe, Vice-Captain of the First Division. His robes were torn, his body streaked with blood from terrible wounds. With a groan, he collapsed forward onto the ground.
"Chōjirō!" Ukitake shouted, rushing to his side.
Unohana Retsu and Isane Kotetsu were already kneeling beside him, beginning emergency treatment. But the expressions on their faces made it clear—the injuries were dire.
Shunsui's sharp eyes focused on the slashes across Sasakibe's chest and back. His expression tightened. These wounds… why do they look so much like Kageoni—my own Katen Kyōkotsu's technique?
The air grew tense. A heavy silence fell—until another presence appeared.
A tall, gaunt figure emerged from the mist, his long, messy brown hair framing tired, shadowed eyes, as though he hadn't slept in days.
Miyako's sharp gaze locked onto him. He knew immediately who it was.
Muramasa. Even here in Soul Society, he's one of the most dangerous and unique Zanpakutō…
Miyako's jaw clenched, but he stayed quiet. Good. With Aizen focused on Hueco Mundo and the Hōgyoku, at least he won't be meddling in this… for now.
"The Captain-Commander will not be coming," Muramasa said coolly, his voice steady but carrying a strange, chilling calm.
"What did you say?" Komamura Sajin barked, stepping forward. His massive frame blurred as he used Shunpo to confront Muramasa directly. "If you've done something to Captain-Commander Yamamoto, then I'll make you talk!"
He drew his blade in a single fluid motion, slashing down toward the intruder.
But Muramasa simply leapt back, his movement effortless, almost lazy. With a wave of his hand, a gust of spiritual wind surged outward, buffeting everyone present.
Miyako's eyes narrowed. He felt the strange current instantly, probing, invasive. With his unique ability—the God-Rejecting, Soul-Severing edge—he could sense every foreign attempt at breaching his spirit and Zanpakutō.
So this is Muramasa's power… trying to forcefully connect with our Zanpakutō spirits.
He smirked faintly. Too bad for you… mine won't bend that easily.
But Komamura wasn't backing down. "Bankai!" he roared. "Kokujō Tengen Myō'ō!"
The massive armored giant rose behind him, its titanic blade swinging down toward Muramasa—
—and then, to everyone's horror, that very blade veered, slashing straight at Komamura himself.
"What—?!" Komamura barely managed to block, staggering back.
Gasps erupted around the Captains and Vice-Captains as the colossal warrior shimmered, its form breaking apart. Kokujō Tengen Myō'ō dissolved, reshaping itself into a figure equal in height to Komamura—an independent spirit standing face-to-face with its master.
"Impossible…" Komamura growled.
But he wasn't the only one.
Tōshirō Hitsugaya immediately tried to step in, his voice ringing out clearly:
"Sit upon the frozen heavens… Hyōrinmaru!"
But nothing happened. His Zanpakutō remained silent in his hands.
"What?!" Hitsugaya's eyes widened.
The same thing occurred with Suì-Fēng and the others—their Shikai calls yielded no response.
"What's going on…?" someone muttered, faces turning grave with realization.
Muramasa stood calmly, eyes closed, a knowing smile playing on his lips. "It's simple. Because I've already released your Zanpakutō, they are no longer on your side."
Suddenly, blood trickled from one of Muramasa's eyes. With a casual wave of his hand, explosions of fire and light erupted across the darkened Seireitei.
"You bastard… what did you do?!"
Muramasa's grin widened. "Not me. This is what your Zanpakutō desired. They are no longer chained to you. They are free… completely free from the Shinigami's control! Hahahaha!"
"Who the hell are you?!"
Muramasa raised his hand dramatically, his voice carrying across the battlefield. "My name is Muramasa. The Shinigami's reign over Zanpakutō ends tonight. From this night onward, the Zanpakutō shall rule—"
His words stopped short. His gaze snapped toward Amamiya Miyako. Unlike the others, the twin blades hanging from Miyako's waist still pulsed with unmistakable spiritual pressure.
Muramasa's eyes narrowed.
"What's the matter?" Miyako stepped forward calmly, voice steady, a faint smirk on his face. "Didn't you just say all Zanpakutō were freed from their restraints?"
"You…" Muramasa's expression darkened. He waved his hand once more, attempting to drag Miyako's blades out.
But nothing happened. The twin blades at Miyako's side refused to answer Muramasa's pull, as if something unseen was protecting them.
"Separate… Shinya Zetsunen."
Miyako drew his Zanpakutō, the blades ringing sharply in the tense silence. As the release command echoed, the twin swords fused and reshaped into a black-and-white bow, spiritual energy thrumming like a heartbeat.
Miyako leveled his gaze at Muramasa, smiling faintly. "How about I drop my guard this time… and you try again?"
"Miyako, stop this at once!" Rukia shouted, panic flashing in her eyes. "If Muramasa succeeds in releasing your Zanpakutō, then we'll have no one left to fight!"
"That's too reckless." Ukitake's voice was firm but strained, stepping forward with concern. "My Zanpakutō won't even respond anymore. We can't risk losing yours as well, Miyako-kun."
Miyako tilted his head, almost playfully. "Don't worry, Rukia, Ukitake-taichō. Trust me… I know what I'm doing. Now then, Muramasa—didn't you say you wanted to try again?"
Muramasa's composed expression finally cracked into anger. "How dare you look down on me!" He thrust his spiritual pressure toward Miyako, dark energy rushing into the bow clutched in his hands.
This time, there was a reaction. The black-and-white bow shuddered and glowed, energy building until it splintered and collapsed. The form of Miyako's Zanpakutō reverted back to twin blades—yet from that light, a figure began to emerge.
A human form materialized beside Miyako: a black-haired, white-clad spirit stretching his arms lazily. His voice was calm, almost mocking.
"Miyako, you're being awfully lazy this time."
Miyako grinned. "Not lazy. I just figured if someone wants to do the dirty work for me, why not let them? Would've been a waste otherwise."
Everyone stared, their eyes wide. Even as their own Zanpakutō had been stolen away, Miyako's spirit had manifested right before them.
"Attack!" Muramasa snapped. "Obey my command and attack him!"
But as he shouted, his words faltered. Something was wrong. He realized—he didn't even know this Zanpakutō's name.
The manifested spirit—Zetsunen—only whistled nonchalantly.
Miyako stepped up beside him, resting a hand on the hilt of one blade. "My Zanpakutō has a name. It's Zetsunen. Didn't you hear him just now?"
Muramasa's eyes burned with confusion and frustration. "…What did you do?"
Miyako smirked knowingly, his voice low, almost playful. "Good question. What did I do…?"