Because both the Soul Society and Hueco Mundo were worlds with extremely volatile spatial fluctuations, opening a passage between them wasn't particularly difficult.
With the support of the Technical Research Bureau, led by Senjumaru Shutara and others, the necessary preparations were completed in just three months.
A stable, massive Dangai passage was finally established between the two worlds—large enough to allow hundreds of Shinigami to pass through simultaneously.
Once everything was ready, the preparations for the Hueco Mundo Expeditionary Force were complete.
On an auspicious day, at an auspicious hour, the captains of the Gotei 13, led by Yamamoto Genryūsai Shigekuni, along with all vice-captains and officers of third seat or higher, gathered for the ceremony.
The first-ever official expedition under the banner of the Gotei 13 unfolded on a desolate, ancient plateau.
Yamamoto stood at the forefront.
Before him stood the neatly assembled Hueco Mundo Expeditionary Force, each member adorned with bronze pauldrons bearing the character for "Guard" (護) on their right shoulders.
Only vice-captains and above were exempt from wearing the armor—they didn't need it.
As he gazed at these young warriors about to venture into the unknown, even Yamamoto Genryūsai Shigekuni couldn't help but feel a surge of emotion.
In his thousands of years of life, he had never before witnessed an army marching beyond their world under the banner of an entire realm.
After a long silence, he suddenly barked out a command:
"Salute!"
In response, the Gotei 13 members behind him struck their chests with their fists in unison, producing a deep, resonant thud.
Clearly, this salute had also been designed by Fujimiya Makoto.
Standing among the ranks of the Expeditionary Force, Fujimiya couldn't help but let out a stifled snort at the sight of this sudden display, barely holding back laughter.
However, for all the Shinigami present, this farewell carried a special significance.
This was the first time they would breach the boundaries of their world, waging war in the land of Hollows, facing unprecedented challenges—no one knew what awaited them in that other world.
Naturally, many of the Gotei 13 members looked upon the Expeditionary Force with genuine admiration in their eyes.
The ones who seemed most at ease were the captains and vice-captains at the front.
Senjumaru Shutara stepped gracefully out from the Gotei 13 ranks.
The elegant woman's face still wore that same cold smile, her narrow eyes carrying a sharp, almost mocking glint whenever they settled on anyone, like the tip of a needle.
"Quite the grand spectacle, isn't it?"
Senjumaru's voice was unhurried as she approached Ganryū, Kifune, and the others, her tone light and teasing.
"However, don't forget the special materials I noted in the memorandum. If you find them, make sure to collect them—no matter the cost."
"How ruthless, Lady Senjumaru."
Ganryū's expression remained as indifferent as ever, like a middle-aged man with no vitality.
As the nominal commander of the Expeditionary Force, leading Kifune and Kamui Unohana into battle, he was under the most pressure of anyone—surrounded by individuals who were anything but easy to handle.
But before he could finish speaking, Senjumaru had already produced several compass-like mirrors.
And she didn't just give one to Ganryū.
Kifune, Kamui, and even their vice-captains each received one.
"Here."
"What is this?" Ganryū blinked in surprise.
"This device is called the 'Auto-Processing List.' It will be crucial in helping you locate your mission targets."
Senjumaru turned her head with a faint smile, her gaze settling on Fujimiya Makoto, who was yawning lazily in the background. She sighed dramatically.
"Because this boy here barged into the Technical Research Bureau a few days ago, insisting that we create a device to help the Expeditionary Force navigate and track their comrades' vital signs."
"Honestly, it kept me up for several nights. My skin is practically wrinkling like soaked fabric from the lack of sleep."
"Oh?"
Ganryū turned to Fujimiya in surprise.
Only the distracted boy hadn't heard, looking around in confusion.
When he finally met Senjumaru's amused gaze, realization dawned. He hurried over, oozing flattery.
"Lady Senjumaru, you've truly outdone yourself! Next time, you must visit my humble abode—I'll prepare a lavish feast in your honor!"
As he delivered his practiced pleasantries, he tried to pull the last compass from her skeletal hand.
But when he tugged lightly—
It didn't budge.
Fujimiya blinked, turning to Senjumaru in confusion.
The noblewoman took the opportunity to lean in, whispering in a hushed voice:
"However, Makoto-kun, your 'Auto-Processing Device' has been... tampered with."
"So, do be careful."
Hearing that even Senjumaru felt the need to warn him, Fujimiya immediately grew serious, lowering his voice in turn.
"Please elaborate."
Senjumaru glanced over his shoulder at Unohana Yachiru, who was smiling gently in the distance, then looked back at Fujimiya with something like pity in her eyes.
"I just wanted to inform you that this wasn't my doing—it was your dear teacher's special request."
"After learning about this device, she insisted (forced) me to make a few... adjustments."
"To ensure you encounter enemies capable of pushing you to your limits, all for the sake of 'breakthroughs.'"
"Your Auto-Processing Device might... occasionally malfunction."
Fujimiya followed Senjumaru's gaze to Unohana, his expression turning strained.
"Such as?"
Senjumaru smiled sweetly. "Such as... while tracking an Adjuchas, you might suddenly find yourself ambushed by a Vasto Lorde. That sort of thing."
"Huh?!"
Fujimiya's eyes nearly bulged out of his skull.
Are you trying to get me killed?!
Senjumaru patted his shoulder meaningfully with one of her skeletal hands.
"Do try to survive, Makoto-kun."
"We all have such faith in you."
Fujimiya swallowed hard under her pointed gaze.
You really don't have to have that much faith in my talent!
Unfortunately, before he could think of a way to beg for mercy, Senjumaru had already Shunpo'd back into the Gotei 13 formation.
She exchanged a glance with Unohana Yachiru.
Both women smiled.
These two...
Fujimiya's face twisted into a grimace.
Just how ruthless is this teacher of mine?!
"BZZZT—"
Just as the boy was lost in his misery, a massive spatial distortion tore through the air behind him.
Ganryū thrust his Asauchi into the air, twisting it like a key.
The sky and earth split apart simultaneously.
Every Shinigami present watched in silence.