When Kenpachi used Kidō against the Adjuchas in Mole City.
Gosuke Shigure observed the six-headed Gillian—massive, lumbering, and idiotic—with a contemplative gaze.
He hadn't stepped forward and spoken before Zaraki Kenpachi out of arrogance or to flaunt his skills. That wasn't his style.
Rather, he wanted to test the strength of his body.
Though he had been reborn with the full memories and combat instincts of his past life, he had yet to engage in an actual battle since reincarnation. He was satisfied with his new physical form—but satisfaction is no substitute for field data.
These Gillians made for perfect test subjects.
Despite being Menos Grande, Gillians were the lowest among the three classes—Gillian, Adjuchas, and Vasto Lorde.
For a vice-captain of the Gotei 13, handling a few Gillians wasn't exactly out of the ordinary.
As this thought flickered across his mind, Gosuke moved with sudden precision. His Zanpakutō, which hung quietly at his waist, flashed from its sheath in the same instant.
He did not activate Shikai.
Instead, he swung the blade in its sealed state, clean and decisive.
Spiritual energy surged from his core, channeling through his arm and into the blade. A Shinigami's internal Reiryoku is vastly denser and more refined than the ambient Reishi found in the surrounding air. When released in such quantity, it creates a potent spiritual pressure differential.
This differential is Reiatsu.
A powerful Shinigami can manipulate this Reiatsu not only to suppress weaker foes but also to augment offensive techniques. When concentrated into the Zanpakutō, it becomes something else entirely—sword pressure.
A gleaming white arc of energy sliced through the air.
In a single blow, one Gillian's mask was cleaved clean off. Its massive head hit the ground seconds before it realized it had died. Then its titanic body followed, crashing forward and halting the advance of the Gillian behind it.
But the second Gillian didn't react—not because of discipline, but because it lacked the intellect for rage. The attack came too quickly, too cleanly.
Gosuke didn't pause.
His blade flashed again, and then again—cutting through three more Gillians. He had deliberately maneuvered them into a tight formation, aligning their towering bodies in a perfect line.
Four in one stroke.
It wasn't coincidence. Gosuke Shigure had planned it from the start.
Quadra kill. Close to a pentakill—but not quite.
That lone Gillian that broke the chain left him slightly irritated.
To vent this mild frustration, Gosuke used Shunpo to reposition. In a blink, he was beside the final two Gillians. Two quick thrusts—each precise and economical.
The last two fell. All six had been eradicated.
He hadn't used Shikai, yet couldn't help but push himself. In his previous life, Gosuke had waded through countless wars. Enemies like these—slow, low-intellect Hollows—were hardly even warm-ups.
He didn't need flair or technique for this.
What he needed was calibration.
He had to know if his current body functioned as expected. If it could keep up with his reflexes, his instincts, his mind.
So far, it wasn't bad.
His past-life experience gave him a distinct advantage, but the body was still new—unproven in real combat. Satisfied as he was with its condition, there could still be hidden weaknesses, imbalances, or latent injuries.
Even Kuchiki Aojun—Byakuya Kuchiki's father—was once vice-captain of the Sixth Division. He looked the part, held status, but still died in battle due to a frail constitution.
This fight had taught Gosuke more than he expected.
Perhaps because he had survived so many battles under Kenpachi in the past, this body had unusually sturdy bones. His Reiatsu wasn't at vice-captain level yet—not truly—but it was certainly on par with seated officers. Considering the Eleventh Division's rigorous selection process, he was more than qualified to hold the position of vice-captain.
Still, the strike that killed the first four Gillians had drained nearly half his Reiryoku.
Yet he wasn't concerned.
Unlike physical strength, which was mostly innate, spiritual energy could be cultivated. There were various methods to augment Reiatsu—some conventional, others not.
Hollowfication, for example, artificially multiplies a Shinigami's power. Arrancars undergo the reverse, ripping off their masks to become more humanoid and gain greater control over their spiritual power.
Of course, these are considered unorthodox.
The more accepted method is through Zanpakutō liberation.
Activating Shikai typically multiplies Reiatsu by a factor of one or two. But Bankai is in a different realm altogether—it multiplies that by five to ten, depending on the individual.
And only those with sufficient innate spiritual strength can achieve Bankai in the first place.
Once a Shinigami achieves Bankai, their Reiatsu—by default—meets or exceeds the threshold required of a captain. It's why mastery of Bankai is the unofficial requirement for captaincy in the Gotei 13.
In short, achieving Bankai often means you've earned the right to lead.
As for Gosuke Shigure, he currently possessed Shikai—but had not yet attained Bankai. Which meant there was still enormous room for growth.
And in truth, the one inhabiting this body now—reborn into the Soul Society—was no mere soul. He was a seasoned warrior, a ghost of countless battles past, with knowledge of arcane methods to increase spiritual pressure and fortify the flow of Reiryoku within the body.
After evaluating his internal state, Gosuke's attention shifted once more to the ongoing battle—Kenpachi Mole City versus the Adjuchas.
Strangely, though Gosuke was only the vice-captain, he had ended his battle faster than the Eleventh Division's captain.
But there was a simple reason for that: Gosuke's enemies had been six simple Gillians—hulking but brainless.
Kenpachi's opponent, on the other hand, was an Adjuchas—a more intelligent, faster, and significantly more powerful class of Menos Grande.
Had Kenpachi chosen to fight with his Zanpakutō, the Adjuchas likely wouldn't have lasted as long. But for some reason, he didn't draw his blade. In fact, Gosuke hadn't even seen it on him. Instead, Kenpachi fought using Kidō—an odd choice, especially for someone from the Eleventh Division.
And yet, it was surprisingly effective.
Kenpachi's single-handed Kidō casting was precise and aggressive. Gosuke watched, mildly impressed, as the captain bombarded the Adjuchas with spell after spell—wearing it down with unrelenting efficiency.
Finally, Kenpachi unleashed a devastating Kidō technique—Fiery Lightning Howl—a fiery thunderstrike that vaporized the Adjuchas in a blast of burning lightning.
With that, the seven invading Menos Grande were eliminated—courtesy of the captain and vice-captain of the Eleventh Division.
Afterward, Kenpachi glanced over at the pile of Gillian corpses. He didn't bother collecting them. There was no need.
Dead Gillians disintegrate soon after death, breaking apart into Reishi particles, which return to the atmosphere of Rukongai.
What caught Kenpachi's attention wasn't the corpses—it was Gosuke Shigure.
The vice-captain had ended his side of the battle swiftly, precisely, and without activating Shikai. And that fact alone made Zaraki Kenpachi of Mole City take notice.