Nanatsuki remained at Las Noches for a while, offering personal guidance to both Grimmjow and Ulquiorra.
Neither of them had ever undergone formal training—their growth had relied entirely on raw talent.
"This thing really works better than my claws?" Grimmjow muttered, repeatedly practicing suburi swings with his Zanpakutō. He found it awkward—his grip unnatural, the balance off.
Nanatsuki had already evolved Grimmjow into an Arrancar as well. But just like Nelliel two decades prior, Grimmjow's accumulated strength at the time of transformation was lacking. He wasn't able to become a Vasto Lorde-class Arrancar yet.
"You only just gained a human form—it's normal that you feel out of place," Nanatsuki said with a smile. "In a battle between Hollows and Shinigami of similar Reiatsu levels, Hollows usually lose. The reason? Shinigami possess a wide array of disciplines—Zanjutsu, Hakuda, Kidō, Zanpakutō techniques—making them far more adaptable."
"Then I just need my Reiatsu to overpower them, right?" Grimmjow grinned. He'd been a panther for so long he still preferred claws over swords.
"If Sosuke was here, he'd probably agree with you," Nanatsuki chuckled. "But Sosuke's strengths go well beyond just strong Reiatsu."
"Reiatsu growth has limits. When you're facing someone on your level—or someone stronger—it's your skillset that becomes your edge," Nanatsuki said, drawing his sword. "Let me show you. I'll suppress my Reiatsu to match yours."
"You're going to match me?" Grimmjow's confidence spiked. "Then there's no way I'm losing!"
He believed in his combat instincts. He may have lacked formal training, but he'd grown up surrounded by corpses, slaughtering his way through Hueco Mundo. Years of survival forged battle instincts sharper than steel.
Nearby, Nelliel and Ulquiorra paused their training, turning to watch.
"Ulquiorra, have you ever seen Sensei fight?"
"I've seen him—but I didn't even register his movements before I was defeated."
"Then watch carefully. When Sensei teaches, he won't overwhelm us with brute strength."
"Mhm."
Grimmjow, having received Nanatsuki's signal, didn't hesitate. He charged.
Still unused to his sword, he reverted to his panther-like form.
"Claws still feel best!" he roared, laughing wildly.
Even before becoming an Arrancar, Grimmjow had always been known for speed.
Now, as an Arrancar, he was faster than ever.
In pure movement speed, he even surpassed Nelliel and Harribel—neither of whom specialized in speed.
However, battle-speed in Hollow combat factored in Sonído usage—essentially manipulating Garganta space. In that domain, Nelliel and Harribel still outclassed him.
Grimmjow closed the distance in an instant, his black claws slamming into Nanatsuki's Zanpakutō.
Clang—!
The impact rang like colliding steel. Grimmjow's claws were every bit as hard as a Zanpakutō.
Yet he was the one forced back several paces, while Nanatsuki stood motionless.
"Didn't you say you'd match my Reiatsu?!" Grimmjow accused. Equal Reiatsu should mean equal impact—so why had he been repelled?
"That was Zanjutsu technique—Blade Rebound Counter," Nanatsuki replied with a calm smile. "Even with equal Reiatsu, I redirected the force using your own opening."
Blade Rebound Counter was a technique that used spiritual pressure to exploit an opponent's weakness, rebounding their strike with added shock.
"An opening, huh?" Grimmjow scowled. Reiatsu surged within him as he leapt back in, faster now.
"If I'm fast enough, there won't be any openings!"
Shff—shff—shff—
Grimmjow blurred into motion, leaving multiple afterimages around Nanatsuki.
His pure movement had already reached a level akin to Shunpo.
Clang! Clang! Clang!
His claws struck like slicing gales—but each blow was precisely intercepted by Nanatsuki's blade. He couldn't land a hit.
And worse—his claws were beginning to go numb from the impacts.
'He's finding my weak points instantly...!'
Grimmjow was stunned. His speed had exceeded visual tracking, yet his teacher still located his flaws and countered them with surgical precision.
'This won't work!'
He leapt high, shaking out his arms to relieve the numbing shock.
Reiatsu surged toward his claws, and brilliant azure light began to gather.
"This is the technique I mastered after evolving!"
Grimmjow's smile widened. He was confident in this new move—it was stronger than even his Cero.
Blue energy crackled as five massive claw-like blades formed on each hand.
"Panther King's Claws!"
He slashed downward—ten luminous claw-blades rained toward Nanatsuki like falling stars.
At that moment, Nanatsuki released the blade he was holding between two fingers—and swung upward.
A single arc of blue light flew from his Zanpakutō, meeting the ten descending claws.
Grimmjow's eyes widened. The move looked eerily similar to his own technique—just with a different delivery.
Panther King's Claws was, at its core, a Reiatsu Blade technique—something Nanatsuki had mastered long ago.
The blue arc struck.
CRK—KRACK—
The claws shattered instantly—cleaved in half by the sweeping light.
"What?!" Grimmjow reeled. He could tell Nanatsuki hadn't used much Reiatsu—so how had the attack been that devastating?
His Panther King's Claws could tear through Adjuchas-class Hollows like paper…
Yet they were destroyed in a blink.
The arc veered slightly before hitting Grimmjow and instead bisected the dune behind him.
"That little Reiatsu—yet so much power… Is that what swordsmanship really is?"
Ulquiorra quietly analyzed the slash. He sensed it had consumed even less Reiatsu than his own Lance of Lightning.
But against that arc, even Lance of Lightning would be sliced cleanly apart.
The gap between him and his teacher was too large to quantify.
"Sensei's swordsmanship is profound," Nelliel nodded solemnly. "Don't underestimate him just because his attacks seem effortless."
"Yeah... that was amazing," Grimmjow said, stepping forward, clearly impressed. "Sensei—I want to learn swordsmanship from you!"
"Practicing Zanjutsu will refine your control over Reiatsu Blades. In time, your Panther King's Claws will become sharper, stronger."
A notification popped up on Nanatsuki's interface:
[Instructing Grimmjow Jaegerjaquez: Advanced Reiatsu Control Training (In Progress)]