The Soul King Palace existed far above the Soul Society, suspended in the upper reaches of the Reishi Sea, and between it and the world below stood seventy-two separate barriers—each one denser and more absolute than the Sekkiseki-reinforced Kekkaisurrounding Seireitei.
In the earliest eras of Soul Society, these seventy-two barriers had not yet been erected. At that time, powerful beings could, with enough force or recklessness, attempt to breach the Palace and intrude upon the Soul King's domain.
But the members of the Royal Guard—Squad Zero—realized that continued assaults would eventually risk damaging the Soul King's seal. If anything were to happen to the Soul King, the balance of the worlds would collapse. Thus, with the aid of the overwhelming divine reiryoku that permeated the Palace's realm, they constructed the seventy-two barriers, isolating the Palace from every realm below.
Only with the use of the Tenchūren, a vessel forged from the Soul King Palace's own supersaturated spiritual material, could beings ascend or return safely.
Powered by the Shiba Clan's unique launch device, the Tenchūren blasted upward like a comet. Within seconds it impacted the first barrier—shattering through—and then the second, again breaking through, and so on until all seventy-two layers had been pierced. Only after breaching the final barrier did the vessel exhaust its momentum and begin to descend softly, falling not back into Soul Society but landing onto one of the enormous floating platforms that made up the outer structures of the Royal Palace.
Simultaneously, in several of the Five Royal Palaces (Goteiōgan), the other three active members of Squad Zero set aside their work.
They began making their way toward the Inner Sanctum, preparing to greet their new member.
The Inner Palace was the core of the Soul King's realm, and the closest location to the Soul King himself. Every member of the Royal Guard, upon first arriving at the Palace, underwent a ritual in which their bones were reforged by the Soul King's power—creating their individual Ōken—and only then forged their personal Royal Palace.
Since this ritual required exposure to the Soul King's power, all welcoming ceremonies were held in the Inner Palace.
It was also there that Ichibei Hyōsube, First Monk and oldest member of the Royal Guard, would reveal to new members the true history of Squad Zero, the role of the Royal Guard, and secrets about the Soul King known to no one outside the Five Royal Officers.
The Tenchūren settled onto the platform with a muted thud, and a panel slid open on the cylindrical vessel.
Gosuke Shigure, Hikifune Kirio, and Shutara Senjumaru stepped out.
The moment Hikifune set foot outside, she felt an overwhelming flood of reiryoku—so dense it was almost liquid. The concentration of reishi in the air was beyond anything she had imagined.
"So this is the Soul King Palace… The reishi density is unbelievable," she murmured.
Gosuke Shigure nodded. "As expected of the realm that houses the Soul King. The reishi here is several times denser than even Hueco Mundo's. A vice-captain arriving here unprepared might suffocate from the pressure alone."
Shutara Senjumaru gave a small, elegant nod. "This is the Soul King's domain—the foundation upon which all realms rest. It is natural that it surpasses everything below."
She turned to Gosuke. "I will take you to my Royal Palace—Shutara Palace. You may stay there for now. When Hikifune's induction ceremony is complete, I will come for you."
"Understood," Gosuke replied.
During this exchange, Hikifune's curiosity continued to grow.
She understood Senjumaru well—they had worked together in the Twelfth Division for many years—but she had no idea how Gosuke had established such familiarity with her, nor why Senjumaru treated him with such closeness. Their relationship puzzled her more with every passing moment.
Senjumaru guided Gosuke first.
The Soul King Palace was a massive city-state floating in the heavens, yet paradoxically, movement through it did not involve flight.
This was normal. A Shinigami's ability to "fly" or hover existed only in realms where ambient reishi density was lower than the reishi making up the Shinigami's own body—such as the Human World.
In Soul Society or Hueco Mundo, Shinigami could not actually fly, merely run through the air using footholds formed from reishi. But here, in the Palace, even that was impossible—the reishi density exceeded even a captain's tolerance. For vice-captains, simply standing here could feel suffocating. Flight was utterly impossible.
To travel between the Palace's various regions, one used the public transport platform known as the Omotesando—a massive semicircular platform suspended in midair.
Senjumaru brought both Shigure and Hikifune to the Omotesando, delivering Gosuke to her Shutara Palace first. Afterward, using the same platform, she took Hikifune toward the Inner Palace, the main sanctum where the Soul King's power could be accessed.
When they arrived at the gates of the Inner Palace, three figures were already waiting.
Senjumaru introduced them to Hikifune one by one.
"The High Monk—Ichibei Hyōsube."
"The Blade God—Ōetsu Nimaiya."
"The Armorer—Kirio Hikifune… pardon, the Armorer, Tenjirō Kirinji."
"And myself—the Great Weaver, Shutara Senjumaru.
These are the current members of Squad Zero."
Ichibei chuckled when Senjumaru finished her introduction. "Shutara, you misspoke. We are no longer four—we are now five."
He stepped forward, raising a massive calligraphy brush.
"The Soul King has already granted revelation. From this moment onward, Hikifune Kirio, titled Valkyrie of the Valley, shall serve as the South of the Five Royal Guards."
"Her Palace shall be established to the south of the Inner Sanctum."
Turning to her, Ichibei offered a deep, formal bow.
"Hikifune Kirio—welcome to Division Zero."
Ōetsu Nimaiya and Tenjirō Kirinji grinned as well.
"Welcome to Squad Zero!"
"Good to have ya, Kirio!"
Their joy was palpable. Since the ancient past, Squad Zero had never numbered more than five members. In the beginning, it was only Ichibei. Later, Ōetsu joined; then Kirinji; then Senjumaru. Now, after countless ages, a new companion had finally arrived.
For them, gaining a new member was a rare event—one that might come only once in hundreds of thousands of years.
And barring catastrophe, anyone who joined Squad Zero would remain with them indefinitely.
Thus, they treasured each new comrade deeply.