Soul Societies.
Disclaimer: Skymaster23 has no connection to Bleach.
This story was thought-up before the Burn The Witch spin-off was announced, so nothing from it will be included unless requested.
My sincerest apologies for the constant revamps. I'm a perfectionist, so it just took me this long to figure out how it should be structured.
Prologue.
Rukongai (unknown district), 1871.
An individual is walking around a forest when he hears faint splashing sounds. "That noise? Could it mean..." He asks himself eagerly and heads towards the source. "Salutations, kind sir or madam! It has been many a day since-" He starts to say before hearing a shriek.
"Mi-minaide!" The kind person yells before tossing a large rock at his face.
Once he extracts it, he glares at the person, who he sees is a girl around his age, and immediately turns around. "What, pray tell, did you do that for?!" He asks loud enough for her to hear, and is about to toss the rock aside before noticing that there's a layer of ice covering it.
Yonban-tai courtyard, 2005.
After recalling Minazuki, Unohana turns to leave. "There is somewhere i want to go." She says, only to stop after a few paces. "But... if I'm correct, they may need to know of this sooner rather than later." She tells herself, and vanishes for a bit before returning with a jigokuchou.
"Wait, you're not planning on asking for him to come here already?" Her fukutaichō asks as Unohana draws her zanpakutō again and opens a senkaimon before saying something to the messenger and sending it in. The pair depart in a certain direction.
Elsewhere, a person is at his desk when the messenger flies in.
Back with the two shinigami, they are several miles into their journey when they are met by a figure in chainmail and a tabard with the Latin number 7 on it. "This must be big if someone like you seeks our aid." He says while narrowing his eyes.
"What was that?!" The fukutaichō asks while taking a step forward, but Unohana glances at her.
"Now is not the time for old wounds, Isane."
"...Very well, it would explain all the fluctuations we've been detecting lately. Just what do you have in mind, and why call us?" The newcomer asks her as he looks towards the execution hill for a moment.
"Several days ago, the Goban-tai Taichō, Aizen Sōsuke, was found dead." Unohana tells him.
"What? From what I've heard, there are only three aside from you who could match him, even by surprise." He says aloud.
"That is part of why i sent the summons... i suspect a fourth."
"And who would that be?" He asks warily, but before she could answer, a heaviness is felt. "Wha-why is it getting warmer all of a sudden?"
"That would be the Sōtaichō, but we must continue." Unohana explains as she helps Isane stand up again.
"Where to, Taichō?"
"Chūōshijūrokushitsu."
After a bout of panic from the fukutaichō, the three make their way to the government district, and all turn to see a burst of pale-blue light from the hill. "Now what; isn't that one of those spells of yours?" He asks, only to gasp as a cloud of dirt as big as the nearby spire appears. "What the hell did you get me into, the end of the world?" He then asks, thinking that for a second, it almost looks like a skill he's seen before.
"Calm yourself." Unohana tells them, only to see three others in the distance, but says nothing. "We must keep going." She says next before she started running.
Once they arrive, the newcomer raises a brow. "This person you called us about sure must have been an impatient one." He quips when seeing the broken door.
Unohana says nothing.
As they reach the underground assembly hall, however, Isane places her hands over her mouth as they see the carnage. "Every last one..." She says aloud.
"How can this be? It's though they were all killed simultaneously." The newcomer observes as he stands by one body slumped over as if attempting to jump over the table. "Captain?!"
While noting the state of the remains, Unohana's hand twitches. "I was right." She says to herself, and heads back outside before performing shunpo.
Almost as soon as Isane and the newcomer caught up, the faint sound of an explosion was heard from the tunnel entrance. The three rushed in to see another disturbing sight. Without even waiting for the boy to fall, the newcomer began changing into a large boar. Aizen started to say something, but was cut off as the newcomer vanished for a second and plowed him into the wall of a nearby tower only for a second Aizen to appear and raise a hand. "Hadō no sanjuni: Ōkasen."
Ichiban-tai, Sōtaichō's office.
Two days after the defection, Unohana, Kyōraku, Ukitake, Zaraki, Kurotsuchi, Suì-Fēng, Hitsugaya, Komamura, their fukutaichō, Rukia, and the ryoka are standing. "Any ideas what that geezer called us for?" Zaraki asks outloud.
"Whatever it is, we will wait for him to explain as long as he sees fit." Suì-Fēng told him.
"Peh. Forget that, ya shrimpy bit-" Zaraki is saying when Yamamoto shows up and prods him with his "cane".
"My apologies for bringing you out here despite the condition some of you are in, but recent events demand we all be summoned." Their leader says as he sits down at his desk.
"But if it was not Genryuusai-dono who ordered us here, then who?" Komamura asks aloud.
"We did." Someone calls out, and they all look to the left to see two people walk into view.
"Aren't you the little early-bird..." Kyōraku tells one of them.