"Ah… seeing someone effortlessly create exactly what they envisioned—what a subtle feeling." Kisuke Urahara finished inspecting Muten Natsu's Gigai. "Using a Zanpakutō's power to craft a Gigai that fits perfectly with its user, then stabilizing it with a special Kidō—this Raku Zetsu is truly ingenious. Could it be the work of the Ise family?"
"Captain Unohana developed it at first, but I never fully mastered it. Later, 8th Division Lieutenant Nanao Ise helped refine it." Muten Natsu's curiosity was piqued. "Is the Ise family especially skilled in Kidō?"
"After all, they are a Shinto priest family in charge of rituals. No one is more skilled in Kidō than they are." Kisuke Urahara stroked his chin. "No wonder… another custom-made creation, huh? Makes the sense of failure a bit less harsh."
Rukia Kuchiki gave him a sidelong glance. "Do you have to wait for someone to ask before you explain anything?"
Kisuke Urahara had a habit of speaking as if every word carried hidden meaning, yet he only ever scratched the surface, sparking curiosity without ever clarifying it.
"It's a complex topic; explaining it fully would take quite a while… I'll try my best." Kisuke Urahara fanned himself. "Let's start with Kidō. Kidō is one of the Shinigami's main combat techniques. It uses incantations to control Reiatsu and activate various spells. Miss Orihime Inoue, you should have a good sense of how this works."
Orihime Inoue touched the hairpin on her head and nodded. To deploy Shun Shun Rikka's barrier, the incantation must be spoken to activate it.
"So here's the question," Kisuke Urahara said, closing his fan. "Inoue-san's incantations are meant for Rukia Kuchiki to hear. So when a Shinigami chants a spell, who is it really meant for?"
Rukia Kuchiki had never seriously considered this before. Though skilled in Kidō, she had always treated it simply as a technique to master, never pondering the deeper mechanics.
Muten Natsu recalled a previous discussion with Retsu Unohana. "The Soul King?"
"Exactly. Though many see the Soul King as just a symbol, his existence undeniably influences everything around us—including Kidō." Kisuke Urahara elaborated. "The Soul King's power is essentially law itself—the same kind of law that makes water flow downhill or clouds drift in the sky. Normally, these laws lie hidden beneath the world's natural order. When we chant a Spirit Word, the corresponding law is awakened. We channel Reiatsu into it, and the power follows that law to take effect—that is Kidō."
Rukia Kuchiki considered his explanation. "So, Eishōhaki is when a Shinigami has learned a specific law and can skip the awakening step, injecting Reiatsu directly?"
Eishōhaki involves simply saying the technique's name without performing the full chant, increasing the speed at which the technique is released.
Just as Sōsuke Aizen did when he defeated Sajin Komamura with the Kurohitsugi.
"It's precisely because the awakening step is skipped that the power is greatly reduced." Kisuke Urahara pointed upward. "Now that you understand the principles of Kidō, you can see why the Ise family excels—they're closer to the Soul King."
"If that's the case," Muten Natsu said, pointing at herself, "someone like me, who isn't skilled in Kidō, must be farther from the Soul King."
Kisuke Urahara smiled warmly. "Or maybe you're just plain clumsy… Though I'd like to say that, it feels a bit rude, so I'll keep it to myself."
Muten Natsu: "..." Didn't you just say it out loud?
"If we go by that logic," Rukia Kuchiki noted, "then Muten shouldn't be able to learn Kidō, right? But he does know several Bakudō."
"By 'several,' you mean Bakudō #1: Sai, Bakudō #4: Hainawa, and Bakudō #8: Seki, correct?"
Muten Natsu did indeed know these three, plus Raku Zetsu, making four in total. "Is there anything special about these?"
"These rely more on your own power and less on applying the Soul King's laws. That's why even someone far from the Soul King can learn them. But the later Bakudō are essentially impossible to master." Kisuke Urahara gestured to Muten Natsu. "As for Raku Zetsu, it's originally meant to intertwine your spiritual energy with your opponent's, using the surrounding spiritual energy to bind them, restraining the enemy. But the way you use it relies solely on your own Reiatsu, supplemented by your Soul Essence Stealing ability. It's a specially modified version only you can wield. A custom-tailored technique of this caliber could only be created by someone from the Ise family."
The frustration Kisuke Urahara had mentioned came from his past attempt to create a Gigai that could enhance a Shinigami's power, which unexpectedly resulted in the Hōgyoku.
Seeing Muten Natsu realize the very creation he had envisioned, after he had spent so much time researching it, naturally stirred complicated feelings.
However, once he confirmed that Muten Natsu's Bokukō Gigai required the combined power of two Zanpakutō and the Ise family's custom Kidō to function, Kisuke Urahara felt much more at ease.
His goal had been to design something most Shinigami could easily use, but the Bokukō Gigai was unique—only Muten Natsu could create and wield it.
Enhanced Gigai usable solely by their creator—Kisuke Urahara had already developed several varieties of those.
"So I'm still one step ahead~" Kisuke Urahara said smugly, fanning himself.
Muten Natsu raised an eyebrow. "I heard that Mayuri Kurotsuchi made himself a daughter."
"That's impressive~" Kisuke Urahara didn't seem fazed at all. He called toward the hall, "Ururu, could you please heat up a pot of tea for us?"
"O-okay…" came Ururu's timid reply from outside.
"That's the situation. My conclusion is that the Bokukō Gigai suits you perfectly and will greatly enhance your power." Kisuke Urahara paused. "As for the other matter… allow me to ask: why do you want to learn and master Hollowfication?"
"I've used Hollowfication before, but combining it with Hell Flames makes my body deteriorate faster…" Muten Natsu shook her head to clarify. "It's not just the rate of deterioration that accelerates—the boost in power is massive. If I can master this power skillfully, even briefly, it would give me a huge increase. At this stage, if I want to improve in the shortest time possible, this is the fastest method."
"You've studied Hollowfication and even saved a Captain and Lieutenant who were in that state," Rukia Kuchiki said, recalling Muten Natsu's account. "So there should be a way to help him."
"I do have a method to stop Souls from engaging in Soul Suicide, but it only prevents it—it also causes those in Hollowfication to lose their power." Kisuke Urahara spread his hands. "As for enhancing power, I can only do so much, but… there are others who specialize in that."