Soul Society's greatest and final technique that a Shinigami possesses is the final release of their Zanpakutō - Bankai!
After releasing Bankai, at the very least, a Shinigami's Reiryoku would surge by 5-10 times.
In addition, the Shinigami would be able to completely control and utilize all the abilities of their Zanpakutō.
The might of Bankai corresponds with the difficulty in attaining it.
Among the entire 13 Divisions of the Gotei 13, according to publicly available information, only the thirteen Captains were capable of achieving Bankai.
In the nearly two thousand years of peace in Soul Society, Captain-Commander Yamamoto had issued an edict to maintain the safety of Soul Society's residents — Prohibiting Captain-class Shinigami and above from releasing their Zanpakutō.
Of course, the prohibition on Captains releasing their Zanpakutō referred specifically to prohibiting Captains from using Bankai.
The disparity between a Captain's Reiryoku and those below Captain-class was too massive. If Captains fully unleashed their Reiryoku, even Vice Captains would be caught up within three kilometers.
Bankai allowed Captains to increase their Reiryoku by 5-10 times. If two Captain-class fighters using Bankai battled, aside from other Captains, all Shinigami within five kilometers would be in mortal danger.
Ailin had never expected that Kōga Kuchiki would actually dare violate Captain-Commander Yamamoto's edict and use Bankai within Soul Society!
However, to Ailin's relief, the purple-haired, gloomy man that appeared beside Kōga didn't stretch his long-nailed hand towards Ailin, but to the Shinigami spectating from the other side instead.
"Kōga, how dare you..." Among them, only Ginrei Kuchiki knew Kōga’s Zanpakutō's true abilities. But even he hadn't expected that Kōga would actually dare use this ability against them.
"Quick, hurry and seal your inner worlds!" Facing Kōga’s ability, after saying just that Ginrei Kuchiki immediately closed his eyes, entering his inner world and sealing it shut.
But Ginrei Kuchiki's warning was clearly too late!
"How can this be..." Before these Shinigami sensed anything else, wisps of bizarre Reiryoku left their bodies, condensing into figures gripping Zanpakutō or other humanoid beings.
"W-What is going on..." Those whose Reiryoku had condensed into shadowy figures didn't know what they were.
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After all, they hadn't fully communed with their Zanpakutō yet. But those who saw distinct familiar forms taking shape from their bodies’ Reiryoku were shocked speechless.
These were the manifestations of their Zanpakutō Spirits, how had they left their inner worlds?
"Hey Tengumaru, what are you doing?"
"Engetsu?"
"Nenshō, why have you come out?"
In that instant, the Shinigami who recognized their Zanpakutō Spirits hurriedly tried communicating. But to their dismay, their calls were completely ignored as these Zanpakutō Spirits turned into blurs shooting towards Ailin.
"Projection—!" Facing the incoming barrage, Ailin didn't dare be negligent either.
Zanpakutō emerged before Ailin, aside from those stabbed into Sword Hill, practically every single blade from his reality marble was projected out.
The dense mass of hundreds of blades hovering overhead left all present Shinigami breathless.
"Retreat, everyone get away from here!"
"This is beyond your capabilities, leave quickly!" Witnessing this, 10th Division Captain Isshin Shiba stepped forth, drawing his Zanpakutō as he unleashed his Reiatsu to shield the Shinigami behind him, preventing them from losing their will to fight under the pressure of those two powerful Reiatsu up ahead.
On the other side, 7th Division Captain Love Aikawa swiftly followed suit, ordering his men to retreat first while erupting with Reiatsu as well.
Receiving their captains' orders, the Shinigami swiftly fled one by one. In the end, only the arrogant Kōga in the sky, Ailin surrounded by hundreds of blades, the inner world-sealing Ginrei Kuchiki and the two Reiatsu-releasing captains, Isshin and Love, remained in this area.
The eruption of Captain-class Reiatsu also attracted the attention of most Shinigami in Soul Society.
The Captains of 2nd Division Yoruichi Shihōin, 5th Division Shinji Hirako, 8th Division Shunsui Kyōraku and 9th Division Kensei Muguruma were all rushing over.
"Phantasm Break!"
Massive amounts of Reiryoku condensed into streams spreading across the blades swirling around Ailin before, with a wave of his hand, they transformed into rows of azure arrows shooting towards the dozens of manifested Zanpakutō Spirits.
Boom Boom!
The gates and alleys around the Kuchiki residence seemed festooned with endless fireworks.
If not for the compound walls being made of Reishi-resistant Sekkiseki stones, at least one-fifth of the sprawling Kuchiki estate would have collapsed from that barrage. Even then, the opposing alley had been reduced to rubble and debris while several cracks ran along the compound walls now. A few more such attacks and even these Sekkiseki walls would crumble.
Whoosh!
Seven to eight figures shot out from the flames, the ordinary Shinigami Zanpakutō having been completely annihilated by Ailin's earlier attack. Even among the Lieutenant-class, several had perished.
These Zanpakutō that emerged were those quick enough to release Shikai the moment the explosions occurred.
By fortune, they happened to be behind 7th Division Captain Love Aikawa and 10th Division Captain Isshin Shiba whose powerful Bankai-level Zanpakutō shielded them, allowing their survival.
After all, Ailin's were merely projections enhanced by "Phantasm Break", still far weaker than real Captain-class Zanpakutō. Relying solely on projected Zanpakutō to bombard Captain-class ones was unrealistic. However...
Clap!
Ailin clapped the hilt guard of his sheathed Zanpakutō, instantly resulting in faint Reiryoku undulations.
Buzz Buzz...
Sensing these undulations, Tessaiga that Ailin had tossed far away earlier suddenly vibrated before transforming into a blur rapidly shooting back into Ailin's grasp.