After the battle between Nel and Harribel, a prompt appeared on Nanatsuki's status interface.
[Disciple Nel has completed advanced training in Reiatsu Control, successfully comprehending the fusion of Cero and Reiatsu Blade techniques. Rewards granted.]
[Reward: 10,000 General Ability EXP]
[Reward: Flowlight: Cero (Beginner)]
"A sword technique fused with Cero?"
Nanatsuki's thoughts stirred as he focused on "Flowlight: Cero."
A moment later, a stream of training memories surfaced in his mind.
"So that's how it works... I still don't fully grasp it without mastering Cero myself."
Nanatsuki immersed himself in the techniques and experiences embedded within "Flowlight: Cero."
This wasn't just a single move. The memory also contained techniques and insights for integrating Cero into the Reiatsu Blade—applicable not only to this move but to others involving the Reiatsu Blade. There were only slight variations, and with Nanatsuki's level of mastery, those variations were essentially negligible.
With a bit of deduction, he could easily adapt the techniques to other moves that used the Reiatsu Blade.
"Now here's the problem: I don't know Cero yet."
Nanatsuki hadn't expected to learn a Cero-based technique before even mastering Cero itself.
He now understood the technique but, lacking Hollow power, he couldn't release Cero—rendering the sword style unusable.
This was precisely why he had brought Nel to Hueco Mundo for practical training.
Although the integration of Cero into the Reiatsu Blade was a technique he created for Nel, he couldn't demonstrate it himself due to not being a Hollow. Nel had to experience the clash between Cero and Reiatsu Blade through battle.
After a short while, Nanatsuki finished organizing the memories.
Looking up, he saw Nel chatting with Harribel.
"Your techniques are impressive," Harribel said, voicing her curiosity. "Throughout the fight, you used much less Reiatsu than I did, yet achieved far greater results."
Except for the final slash that fused with Cero, Nel's other moves consumed little Reiatsu—but each was devastating, easily shattering her Torrent Shield and Water Dragon techniques.
Meanwhile, Harribel had expended far more Reiatsu for less effective results.
"That's the result of long-term training!" Nel smiled brightly. "Hollows still use Reiatsu too crudely. That last move I used—fused with Cero—you should be able to tell. If you can merge innate techniques like Cero into your moves, you'll find them become way stronger!"
"That's easier said than done..."
Harribel furrowed her brows.
Nel made it sound simple, but it was technically true yet practically useless advice—without proper technique, it was impossible.
Though Cero was a natural ability of Hollows, even she only knew how to release it instinctively.
It was like eating food to fill the belly—an innate function. But she didn't know how food digested or turned into energy.
'She has a good teacher.'
Harribel glanced at the Shinigami beside Nel, feeling an unfamiliar emotion well up in her chest—envy.
In Hueco Mundo, she was one of the most gifted Hollows.
Ever since evolving from a Gillian to an Adjuchas and shedding her beastly nature, she'd never devoured another intelligent Hollow.
She considered herself no longer a beast and wouldn't consume sentient beings for power.
Her "diet" consisted solely of low-level, mindless Hollows and spirit particle-rich sand from Hueco Mundo.
Even so, her Reiatsu had grown rapidly.
She was now at the pinnacle of the Adjuchas class—only a step away from evolving into a Vasto Lorde.
And yet, despite all that, today was the first time she had felt genuine envy.
'If only I had a teacher like that...'
"Little Harribel wants to learn? But this is something my teacher taught me—you'll have to become his student too!" Nel spotted the persistent envy in Harribel's eyes.
Her eyes gleamed with thought.
Harribel was just like her—a Hollow capable of suppressing her instincts with reason.
That alone was rare.
Most Hollows would obey their evolutionary instincts and devour one another.
But Harribel could suppress that urge and even had the courage and will to protect her comrades.
Even when facing her, Harribel didn't retreat.
Nel genuinely liked Harribel. She thought they'd make great comrades.
"Sensei~ why don't you accept Little Harribel as your student?" Nel clung to Nanatsuki's arm, speaking sweetly. "She's super talented! She definitely won't tarnish the name of Katori-ryu!"
"Harribel's talent is impressive. She's worthy of being taught. But... shouldn't you ask if she's even willing to become my student?" Nanatsuki gave a helpless smile—Harribel hadn't even spoken yet, and Nel was already jumping ahead.
He too had considered taking Harribel as a disciple.
Unlike Grimmjow, Harribel already had a humanoid form—no issue for sword training.
Even if Arrancar mass production wasn't possible yet, direct apprenticeship was.
"She'll definitely agree!"
Nel said confidently.
The envy in Harribel's eyes had been plain as day—even Nel could see it.
"Am I right?" Nel turned to Harribel with an expectant look.
"If I could be your disciple, it would be my honor," Harribel said seriously. "But... my companions still need me. I'm afraid I can't leave them behind."
They hadn't found a safe resting place yet. The areas rich in Reishi were all occupied.
They had passed through many Hollow territories on their journey. Incidents like the one with the Blackshark King weren't uncommon.
Her three animal-like companions had just evolved into low-tier Adjuchas—if she left them, they wouldn't survive long before being devoured.
Even if they hadn't run into the Blackshark King today, they would've had to leave the Stone Forest soon.
The Blackshark King wasn't a major threat, but the Reishi concentration in this region was still too low for their growth.
They were only staying temporarily to rest.
Both Harribel and her companions were still in their growth phase—they needed to settle somewhere with denser Reishi. The closer to Las Noches, the higher the Reishi concentration.
Their destination was, in fact, Las Noches—the opposite direction from where Nanatsuki and Nel were heading. Nanatsuki had deliberately taken Nel away from Las Noches.
"That won't be a problem," Nanatsuki chuckled. "Nel's training has concluded. She can stay here to help you with the basics."
He had already planned to leave Nel in Hueco Mundo.
As a Hollow, it wasn't convenient for Nel to remain in the Soul Society, nor could she always stay at the dojo.
Hueco Mundo was more suitable for her.
Not wanting to miss this rare chance to learn Shinigami swordsmanship, Harribel dropped to one knee and bowed her head.
"Harribel is willing to become your disciple. Please accept me as your student!"
Seeing the way Katori Nanatsuki and Nel interacted, she was deeply moved.
She had been a solitary soul for so long.
Now that the opportunity for both companionship and mentorship had appeared, she didn't want to miss it.
"Huh? I have to stay in Hueco Mundo?" Nel's face fell as she wailed, "But I don't want to leave Sensei... or everyone at the dojo!"
Just imagining eating sand again made her feel like the sky was falling.
Ever since she tasted Nanatsuki's cooking, she never wanted to go back.
"From this moment on, you are my disciple," Nanatsuki nodded. "Coming to Hueco Mundo isn't difficult—I'll come check on your progress from time to time."
"Back to the days of eating sand..."
Nel collapsed to the ground, her silver-brown eyes losing their shine.
"Why are you acting like Kana already—such a glutton." Nanatsuki smiled helplessly. "Alright, I promise to bring you desserts every time I visit."
Nel adored sweets. Even when Nanatsuki didn't cook, Batsu'unsai would often bring back snacks for her from the confectionery shop.
"F-fine then..." Her eyes regained some sparkle as she forced herself up. "You better not forget!"
Harribel looked puzzled. She couldn't quite understand Nel's extreme mood swings.
"Harribel, focus on the basics with Nel for now," Nanatsuki said. "You're both talented. Right now, Las Noches is without a ruler—I hope one day to see you both claim it."
Leaving Nel behind also served another purpose: for her to take control of Las Noches, turning it into a base for Nanatsuki.
Even though Baraggan was already dead, Las Noches still had many powerful Hollows. Nel couldn't overpower them all.
But with Harribel's help, the odds would improve.
This was Nanatsuki's trial for both of them.
"Teacher wants us to conquer Las Noches?" Harribel's heart skipped. She hadn't expected her new teacher to have such ambitions. "But Las Noches is filled with powerful beings… I don't know if we can do it."
Truth be told, she still didn't even know who her teacher really was—she'd accepted him without much thought.
"I forgot to introduce myself," Nanatsuki smiled. "I'm Katori Nanatsuki, a Captain in the Gotei 13."
"A captain?" Harribel's heart trembled. But soon she understood—only a captain-level Shinigami could be Nel's teacher.
"You didn't know? The one who defeated the King of Hueco Mundo, Baraggan—that was Sensei!" Nel said proudly. "Sensei is the strongest Shinigami!"
She had never questioned whether the Captain-Commander or her teacher was stronger.
Baraggan's name had been infamous in Hueco Mundo.
Like all other Hollows, she used to think Baraggan was stronger than any Shinigami.
But even he had fallen to Nanatsuki.
Which in her mind, created a simple equation:
Teacher > Baraggan > Other Captains
"Don't exaggerate," Nanatsuki flicked her mask lightly. "I'm not the strongest."
"Eh? Really?" Nel covered her head.
"The one who defeated Baraggan and collapsed the Las Noches army was him?!" Harribel was shocked to her core.
She had unknowingly met—and apprenticed under—a living legend.
Baraggan's name had been a symbol of immortality in Hueco Mundo.
Yet this legendary Hollow had been felled by a Shinigami.
A Shinigami who was now her teacher.
'If I take Las Noches... I can protect more like-minded companions.'
Harribel didn't enjoy killing—but she knew that power was the foundation of protection.
Now, with such a powerful teacher, she began to believe that they might actually succeed.
"I'll return to the dojo first to grab some flagfish bokkens," Nanatsuki said.
Harribel's Reiatsu control was still rough—she needed flagfish suburi training to refine it.
"I'm going too! I still have snacks in my room I didn't finish!" Nel added immediately.
"Alright then. Go pack up," Nanatsuki nodded.
He glanced at his status interface, where some messages had just been skipped.
The earlier ones were disciple notifications, but the two that followed were new quests.
[Special Mission: Birth of a New King (Unique). Guide Disciple Nel to become King of Hueco Mundo.]
[Special Mission: Birth of a New King (Unique). Guide Disciple Harribel to become King of Hueco Mundo.]
Nanatsuki focused and read the mission details.
Fulfilling either mission would cause the other to be voided.
Furthermore, if any other Hollow disciples were taken before the mission concluded, they would also be added to this quest.
"Training a new King, huh..."
Nanatsuki closed the interface and left Hueco Mundo with Nel.
Behind them, the animal-faced trio still stood frozen.
They couldn't believe that Shinigami was the one who had defeated Baraggan.
Fear lingered in their hearts—they had barely spoken during the whole exchange.
And yet, they felt relief too. Thank goodness no conflict broke out, or they would've been scattered like sand in the desert.
"He was a Shinigami...?"
"No wonder his Reiatsu felt different. When he healed me, I knew it wasn't Hollow Reiatsu."
"I thought he just had a unique kind of Reiatsu..."
"But... he healed us. I guess not all Shinigami are our enemies..."
"If Lady Harribel and Lady Nel take Las Noches, maybe we'll finally have a home?"
"That kind of future… just thinking about it makes me hopeful!"