"I've taught him pretty much everything there is to teach. As expected of a genius, he learns too fast!" Kazuma tossed and turned in his futon, his mood intensely agitated.
He kept running through mental scenarios on how to better teach Kōga, but his well of ideas had completely dried up.
His restless fidgeting made it impossible for Batsu'unsai, who lay beside him, to get any sleep.
Finally, her patience snapped.
"What on earth are you doing?" she grumbled, rubbing her eyes. "It's the middle of the night, and you're wriggling around like a caterpillar. Even if you don't want to sleep, I do! I have to deal with your mountain of squad duties every single day, and I'm exhausted. If you move one more time, I swear I will tie you to the bedpost with Bakudō."
Kazuma froze instantly, letting out a heavy sigh. "Batsu'unsai, I don't think I have anything left to teach Kōga."
Batsu'unsai yawned, her voice thick with sleep. "Isn't that a good thing? Once he's done, you can sleep in every day and stop complaining about early mornings. Now go to sleep!"
Kazuma was silent for a moment before softly replying, "Oh."
He pulled Batsu'unsai into a tight embrace, but his heart remained filled with anxiety and unease.
Just like that, Kazuma held her all night without catching a wink of sleep. Various teaching scenarios and theoretical problems flashed through his mind.
He began to deeply doubt his own abilities, unsure of how to be the master that Kōga actually needed.
...
Kazuma got out of bed before the sun even crested the horizon, in truth, he hadn't slept at all!
Batsu'unsai blinked awake, looking at Kazuma in surprise. "Why are you up so early today? Not sleeping in?"
Kazuma leaned down and gave her a gentle kiss. "I've made a decision. I'm going to make a quick trip to Hueco Mundo, please submit the border-crossing paperwork to the Captain-Commander for me."
"Going to Hueco Mundo?" Batsu'unsai frowned, sitting up. "Is something the matter?"
"I won't tell you just yet, you'll know when I get back. don't worry, it's a good thing."
Acting on his late-night revelation, Kazuma immediately left the Seireitei, tore open a Garganta, and stepped into the desolate, eternal night of Hueco Mundo once more.
"Mistress, I am here." Kōga arrived at the Seventh Division training grounds bright and early, bowing respectfully.
Batsu'unsai looked at the diligent young noble and sighed.
"You've made a wasted trip today, Kōga. Your master took off for Hueco Mundo before sunrise. I have no idea when he'll be back."
...
"Tsk, tsk. This godforsaken place is as utterly desolate as ever. How the hell am I supposed to find Neliel in all this sand?" Kazuma muttered, suddenly feeling very much at a loss.
His brow furrowed in thought.
A moment later, he decided to flare his dense, stellar Reishi to act as a sonar, pinging the surrounding desert.
Right now, his top priority was to find an Adjuchas-class Menos Grande. Lower-level Hollows were mindless idiots and impossible to interrogate.
Back in the day, Kazuma had taught Neliel how to use Kidō.
If he could capture an intelligent Menos and ask about a Hollow slinging Shinigami spells, he might find a solid lead.
As it turned out, the brute-force sonar method was highly effective.
Before long, Kazuma sensed the dense, chaotic presence of a Menos Grande nearby and immediately used Shunpo to speed off in that direction, praying silently.
'Please let this thing be at least an Adjuchas.'
As he drew closer to the target, the Hollow's bizarre, masked silhouette came into view.
"My luck isn't completely terrible. It looks like an Adjuchas!" Kazuma muttered.
At that exact moment, the Adjuchas noticed a terrifying blur of spiritual energy rushing toward it at extreme speed, but it had absolutely zero time to react.
"Bakudō #61: Rikujōkōrō!"
Before Kazuma even arrived, he had already bound the creature with the Six Rods Prison of Light.
The Adjuchas's masked face was filled with absolute terror as it thought in alarm, 'Is he... a Shinigami? And an unimaginably powerful one at that!'
In a flash, Kazuma stood casually in front of the immobilized Hollow.
He looked at the trembling Adjuchas with a friendly smile. "Hey there, Mr. Hollow. I'd like to ask for some information. If you can provide useful intel, I'll release the binding and let you go. I promise I won't cut you down. Sound fair?"
The Menos Grande looked nervously at the Shinigami.
He was dressed in a black Shihakushō and wore a white haori over it—the undeniable, terrifying mark of a Gotei 13 Captain.
"L-Lord Shinigami, my name is Arashiya. Please, ask whatever you wish! As long as I know the answer, I will tell you everything without reserve."
Faced with a monster who could restrain him from a mile away without an incantation, Arashiya decided to be extremely tactful.
He only hoped this terrifying lord would actually keep his promise.
He had fought and devoured too many rivals to evolve from a Gillian to an Adjuchas; he really didn't want to die here for no reason.
"I want to ask if you've ever heard rumors of a Vasto Lorde-class Menos Grande who can use Shinigami Kidō? Think very carefully, or I'll cut you down."
To emphasize his point, Kazuma casually rested his hand on the hilt of his Zanpakutō.
"Lord... Lord Shinigami, you couldn't possibly be talking about Lady Neliel, could you?" Arashiya stammered, clearly terrified of the name.
Kazuma's brow relaxed. "It seems you do know her. Are there any other Menos Grande who can use Kidō?"
He had made a strict promise with Neliel back then not to spread the Shinigami arts around Hueco Mundo.
"No! I've only ever seen Lady Neliel use it. All the Menos Grande find it incredibly bizarre that she can use Shinigami arts." Arashiya knew that Neliel's bizarre abilities were definitely related to this specific Captain, but to save his own skin, he knew better than to pry.
"Do you know where Neliel is right now?"
Arashiya frantically searched his memory, choosing to tell the absolute truth. "I don't know exactly where Lady Neliel's lair is, but I saw her from a distance traveling through a specific quartz forest not long ago!"
"Give me the coordinates!" Kazuma urged impatiently.
Arashiya hurriedly rattled off a string of landmarks and pointed a trembling claw in the general direction.
"I really hope you aren't lying to me. Otherwise, I will track your Reiatsu down and slowly cut you to pieces. Understand?"
With that cheerful threat, Kazuma swiftly vanished from the spot, speeding off in the direction Arashiya had indicated.
Watching the terrifying Captain disappear over the dunes, Arashiya finally breathed a massive sigh of relief, though his masked body was still shaking.
He couldn't help but complain, his voice breaking into a dry sob, "What kind of rotten luck is this? To run into a monster like that out in the middle of nowhere... I just want to go home..."
However, as he tried to move, Arashiya realized he was still firmly bound by the Six Rods Prison of Light.
He could only pray to the barren sky that Kazuma wouldn't come back, while desperately hoping the high-level Kidō would eventually dissipate and set him free.
After a long journey of interrogating and intimidating various Menos Grande—and effortlessly cutting down the aggressive ones who refused to talk—Kazuma finally picked up a familiar trace of Reiatsu.
He dropped out of Shunpo, calling out to the figure resting on a nearby quartz dune.
"Neliel! It's been a few hundred years! How have you been?"
Sensing an immensely powerful presence rapidly approaching her, Neliel had initially drawn her weapon, fully prepared for a death match. But when she saw the white haori and the familiar, laid-back posture, she dropped her guard in shock.
"Kazuma? Why has your Spiritual Pressure signature completely changed?" she asked in profound confusion.
Kazuma wasn't surprised she hadn't recognized him from afar.
He smiled and explained, "I had a bit of an accident a while back, which forced my spiritual power to evolve to survive it."
Neliel breathed a sigh of relief, sheathing her blade. "It has been centuries indeed, Is there a specific reason a Captain of the Gotei 13 has come wandering back into Hueco Mundo?"
Kazuma grinned. "I came here specifically to find you."
Neliel was somewhat taken aback. "To find me? Why?"
"When we parted ways last time, I asked you for pointers on the Hollow's Sonído technique. Later, I combined those principles with the Shinigami's Shunpo and developed an entirely new, hybrid movement technique. I call it Flash Blink."
Neliel's eyes lit up with genuine warrior's curiosity.
"Oh? What kind of movement technique is it?"
"It's a technique that's fundamentally faster and more fluid than our Shunpo, your Sonído, and even the Quincy's Hirenkyaku," Kazuma explained patiently.
Neliel expressed great interest, leaning in to listen.
Kazuma rubbed the back of his neck. "Here's the thing. I'm preparing to teach it to my wife and my new disciple, but since it relies heavily on your clan's Sonído footwork, I wanted to get your explicit permission first. I gave you my word I wouldn't spread your secrets. Of course, in exchange for your blessing, I'll teach you the Flash Blink technique as well."
Neliel agreed without a second of hesitation. "Kazuma, you didn't have to come all this way! Strictly speaking, Flash Blink is a technique you developed yourself. You have the absolute freedom to teach it to whomever you want. But... I definitely want to learn it too. You better not hold anything back!"
Kazuma smiled warmly. "I wouldn't dream of it. Since the technique incorporates the core mechanics of Sonído, asking for your permission was the only honorable thing to do. Don't worry, I will teach you everything without reservation."
And so, Kazuma spent the next several hours explaining the complex Reishi manipulation and kinetic key points of Flash Blink to Neliel.
He passed on his centuries of understanding and insights on high-speed teleportation without holding anything back.
Neliel listened with rapt attention, occasionally asking sharp, insightful questions and engaging in deep theoretical discussions about spiritual mechanics.
During the breaks, they caught up on their experiences over the past few centuries. Neliel excitedly recounted her various territorial battles and survival stories in Hueco Mundo, which Kazuma listened to with great interest.
In comparison, Kazuma could only offer a helpless, self-deprecating smile; after all, he had spent the vast majority of the last few hundred years in a literal coma, so he didn't exactly have any thrilling adventures to share.
However, happy times always pass quickly, and in the blink of an eye, the shifting Reishi in the atmosphere indicated it was time for Kazuma to return before the First Division noticed his extended absence.
Before they separated, they exchanged precise Reiatsu signatures so they could track each other more easily in the future.
"See you next time, Kazuma. But don't let it be another few centuries!" Neliel said with a warm smile, a hint of genuine anticipation in her eyes.
"Goodbye, Neliel! I promise I'll visit sooner next time," Kazuma replied, waving as he tore open a Senkaimon and stepped through, returning to the Soul Society.
That evening, Batsu'unsai looked up from her desk, surprised to see Kazuma casually strolling back into the office.
"Back so soon? Is everything taken care of?"
The two shared a tender, lingering kiss that would have absolutely infuriated Saitō if she had been in the room.
"It's all taken care of," Kazuma said, resting his forehead against hers. "I'm officially planning to teach Flash Blink to you and Kōga. Speaking of which, where is Saitō? I figure she'll want to learn it too."
At that exact moment, Saitō kicked the door open, carrying a fresh jug of sake.
"Isn't that a stupid question?! Of course I want to learn that absurd movement technique of yours!" she replied fiercely, slamming the jug onto the table.
Batsu'unsai smiled softly.
She knew Kazuma's abrupt trip to Hueco Mundo was likely to secure permission for this exact matter.
Since he hadn't wanted to tell her before it was finalized, he must have had his honorable reasons.
As his wife, she was more than happy to simply trust him.