Nanatsuki was in the yard, guiding Lisa in her sword practice. After Granny Jiang passed away, Lisa stayed at the Katori-ryu Dojo, and Nanatsuki took her in as his disciple.
Everyone at the dojo was very kind to the new girl, helping her quickly feel at home.
"Lisa, swinging a sword doesn't rely solely on arm strength," Nanatsuki corrected her form.
"Let me show you." He took the wooden sword, squatted down, and had Lisa place her hands on his back. "Do you feel that? My back muscles are engaged too."
"Su... such amazing muscles... What am I thinking… I should be focusing on training!" Lisa shook her head, trying to dispel her thoughts.
"Power comes from the back, arms, and wrists working together to drive the sword forward." Nanatsuki swung several times to let her feel which muscles were at play. "Even your legs and waist can contribute. I'll teach you techniques that use them later. For now, focus on the basics."
"Yes!" Lisa responded firmly, but something within her seemed to awaken—the sensation of those perfect muscles lingered on her fingertips.
"Keep training."
Nanatsuki handed the wooden sword back to Lisa and went to check on the other disciples.
"What are you two doing?"
Nanatsuki spotted Shiba Isshin and Aizen Sōsuke tinkering with something together.
Shiba Isshin was naturally outgoing, and not long after arriving at the dojo, he was already buddy-buddy with Aizen.
"Teacher..." Shiba stood up, holding a long rectangular object. Aizen had one too.
"We found these while cleaning the storage room," Shiba explained.
The two objects looked like thin, white plaster strips, each several centimeters long.
"Something from the storage, huh..." Nanatsuki rubbed his chin. "That place is full of random stuff—even I don't know what half of it's for. Find anything interesting?"
That storage was packed with miscellaneous items, some of which even Katori Batsu'unsai couldn't trace back.
"These two seem to be a pair. We noticed they absorb Reishi and have a strange Reiatsu fluctuation inside," Aizen said, showing the item to their teacher.
When Aizen infused Reiatsu into the strip, the previously rigid piece softened slightly.
"Hm?" Nanatsuki's eyes narrowed. His spiritual perception picked up something startling.
After Aizen injected Reiatsu into the strip, it released a Hollow-like Reiatsu fluctuation!
"Let me see." Nanatsuki took the strip. As soon as he stopped infusing Reiatsu, it hardened again.
Once hardened, the Hollow-like fluctuation vanished without a trace.
"Strange… It doesn't seem like a spiritual creature," Nanatsuki remarked curiously. He turned to the two. "The strange Reiatsu fluctuation you felt was actually a Hollow's Reiatsu."
Up until now, Shiba Isshin and Aizen had never seen a Hollow themselves, so without a reference, they didn't realize what they were sensing.
"These things are Hollows?!" Shiba jumped, nearly tossing his strip away.
"Doesn't seem like it. More likely some kind of tool made using Hollows," Nanatsuki guessed, intrigued by their function.
But the strips had no visible seams, making them difficult to open for research.
"Let's ask Batsu'unsai. She might know what these are," Nanatsuki said, noting the strips were still intact.
After all, even Reishi-made objects can degrade over time without maintenance.
Nanatsuki brought the strips to Batsu'unsai, who immediately recognized them.
"Oh, those… I completely forgot where I put them," she mused. "Can't recall the name, but they're little trinkets I took from the Shihōin family. They call them 'Divine Armament.'"
"'Divine Armament'?" Shiba Isshin echoed.
It was a broad term in Soul Society, referring to weapons or tools with unique functions.
"What does this pair do? When Reiatsu is infused, you can sense Hollow energy inside," Nanatsuki asked.
"That's the point. They possess Hollow abilities."
Batsu'unsai raised her foot and stuck one of the strips to the sole of her geta. With a burst of Reiatsu, it softened and adhered to the bottom.
She repeated the process for the other sandal.
"Shinigami, Quincy, and Hollows all have different high-speed movement techniques," she explained.
"Shunpo for Shinigami uses condensed Reiatsu in the feet to create bursts of movement."
"The Quincy's Hiryūkyaku forms footholds by condensing external Reishi underfoot and rapidly shifts them for speed."
"When fast enough, both can appear like teleportation, but they're still just fast movement."
"Hollows use Sonído—true spatial relocation."
Nanatsuki nodded. "So Shunpo is like using your feet as springs. Hiryūkyaku is riding Reishi platforms. Sonído shifts space itself using control over Garganta."
Shiba scratched his face. "Thanks, that makes it way easier to understand. I was always confused by the differences."
"Is this 'Divine Armament' related to Sonído then?" Nanatsuki asked.
Batsu'unsai nodded. "Exactly. It allows Shinigami to use Sonído."
Boom— with a soft drumming sound, Batsu'unsai vanished from sight.
In the next moment, she reappeared beside Nanatsuki.
"This is Sonído?" Aizen's eyes gleamed. "I've read only those Hollows who can open Garganta can use it… but this 'Divine Armament' grants that power to Shinigami."
Nanatsuki asked, "That's a useful ability. Why was it gathering dust in storage? Isn't Sonído faster than Shunpo?"
Batsu'unsai lifted her foot to show him. "It is useful, but as it absorbs Reiatsu, it gradually 'comes to life.' Look—just one use of Sonído and it's already like this."
Nanatsuki saw the plaster had turned into a wriggling white substance. Something was awakening and growing inside.
"...That's intense." He poked it. It didn't react.
He tried peeling it off, but it was firmly stuck to her sandal.
"You can't remove it," Batsu'unsai said. "Once it's used, it fuses with the sole."
"It hasn't absorbed much yet. Starve it for a while, and it'll shrink and fall off."
"It's been dormant for so long it's at its weakest. But with frequent Sonído use, it'll grow rapidly."
"I used it for a while once—it quickly covered the whole sole."
"At that point, controlling Sonído becomes much harder."
"That's why I stopped using it."
Aizen asked, "Is it alive?"
Batsu'unsai thought for a moment. "Not really… but not quite dead either. It could come back to life."
"Let me try," Nanatsuki said, interested in experimenting with the item. A tool that grants Hollow powers to Shinigami had immense research value. He even wanted to bring it to life.
Batsu'unsai removed her sandals and handed them to Nanatsuki.
Luckily, she liked oversized geta, so Nanatsuki could wear them comfortably.
As soon as he stepped in, he felt a strange connection to space.
Nanatsuki was surprised. "This feels like more than just Sonído…"
Batsu'unsai nodded. "It can open Garganta too. All part of the Hollow's spatial manipulation."
Nanatsuki decided to try Sonído first.
He focused on that strange sensation—and something clicked.
Boom— with a light drumbeat, he appeared behind Aizen and placed a hand on his shoulder.
Aizen's muscles briefly tensed, but he quickly masked the instinctive reaction.
"Incredible," Aizen praised. "True spatial movement. There's no visible trace of the motion at all."
At the same time, he thought, 'I'll need to train my spatial perception…'
Nanatsuki asked, "Just using Garganta once won't cause any issues, right?"
Batsu'unsai shook her head. "Opening Garganta takes more Reiatsu. If you use that power, the Divine Armament will grow even faster. But just once shouldn't be a problem. It'll shrink once you stop feeding it."
"Then let me try." Nanatsuki decided to open Garganta. The 12th Division hadn't started monitoring Reiatsu fluctuations across Soul Society yet, so it wouldn't alert Seireitei.
He extended his right index finger and drew through the air.
A black line appeared.
Then black cubes formed at its edge.
The cubes rapidly multiplied and expanded, tearing space open.
Moments later, a black portal large enough for one or two people appeared midair.
Boundless black void stared back at them.
Nanatsuki had opened a Garganta, Hollow-style!
"Amazing… this Divine Armament really lets Shinigami use Hollow abilities," Shiba Isshin gasped.
"Hehehe—" Batsu'unsai laughed with hands on hips. "Cool, right? I won that off Shihōin Senjumaru in a hundred-day sparring match!"
To her, the Divine Armament was mildly useful—but no big deal.
Shinigami had other ways to enter Garganta.
And Sonído's usage count wasn't enough to sustain high-intensity battle.
To her, it was just a neat toy.
But Nanatsuki, who knew what the future held, saw it differently. Hollow power was a crucial puzzle piece for becoming a "Transcendent."
"This Divine Armament can help me study Hollow power," he thought.
He glanced down—and the Divine Armament, once a few centimeters long, had now fully merged with the sandals, dyeing them white.
"Opening Garganta sure accelerated its growth..." Nanatsuki muttered.
"Exactly. And in this state, Sonído becomes unreliable," Batsu'unsai said, reaffirming her opinion that it was just a toy.
Nanatsuki tested it again—his spatial sense had dulled. It was like trying to see through gauze.
He had to focus harder to maintain his connection to space.
Boom— his form appeared before Batsu'unsai.
"Missed..." he frowned. He'd aimed for her left side but landed a dozen centimeters off.
"See? Told you it gets unreliable," Batsu'unsai said. "In battle, that could be fatal. That's why I stopped using it. I'd forgotten all about it until you two found it."
"I'm taking it for further study," Nanatsuki said.
Aizen seemed thoughtful—he sensed his teacher had a deep interest in Hollow powers.
'Hollow abilities really are fascinating…' Aizen thought.
For now, Hollow abilities were just book knowledge to him.
'Hollows do occasionally appear in Soul Society, but it's so vast… the odds of meeting one are low. How can I find one?' Aizen began pondering ways to encounter Hollows.
This was his first time witnessing Hollow power firsthand—and he couldn't help but feel captivated.