The window of this cabin had been opened.
The strands of hair tied to the door and window were just a decoy to catch the attention of anyone meticulous.
The real clue lay in the way the doors and windows were fitted.
This wooden house had been built by him personally. Through his precise design, the way the doors and windows fit was different from the norm.
Once shut, the door or window could still be lifted slightly upward, allowing it to slide just a bit further. When fully sealed, there would be a half-centimeter difference.
Whenever he closed them himself, he would always lift them all the way to that final position.
But now, the window was latched at the normal level.
In other words, whoever closed the window didn't lift it before sealing it!
And on top of that, they had avoided snapping the hair tied to the top, concealing any sign of their entry. Clearly, their intentions were far from innocent.
Katori Nanatsuki stroked his chin as he watched Aizen demonstrate the mechanism.
"Aizen Sōsuke, looks like someone's got their eye on you. Your caution was well-founded."
Aizen replied, "Without caution, it's hard to survive in a place like this."
"But I think... my absence probably drew their attention."
"Back then, I never displayed any spiritual talent in front of Katō."
"He must've come looking for me and realized I was gone—that probably tipped them off."
Nanatsuki nodded.
"I'd like to meet this Katō. But we can't approach him directly—it might spook him."
He wanted to get a look at the so-called "Divine Blade" himself—and while he was at it, set up a few "monitoring points" around Katō.
Aizen suddenly offered,
"I could find an excuse to meet him. That way, I might be able to probe the person behind him."
Since he'd already joined the Katori-ryu Dojo, Aizen wanted to earn his teacher's trust as soon as possible—so he could learn more advanced techniques.
If he could get access to the truly secret teachings, it would greatly benefit his growth.
But Nanatsuki shook his head.
"The waters here run deep. That 'Divine Blade'—one that feeds on spiritual bodies—may very well be tied to the high-ranking noble clans. I don't want you getting involved in this mess."
As a teacher, he didn't want to drag his still-growing disciples into the Kasumioji family's grudges.
A teacher should shield his students from the storm—not send them into danger.
Aizen was momentarily stunned by his words.
He'd spent years roaming the more dangerous areas of Rukongai. Anyone who managed to live out here had either strength, cunning, or both.
He had met Katō during a fight. Friends like Katō weren't rare.
But they were only friends on the surface.
That day when Katō showed off the "Divine Blade," it was just to boast about some "lucky break."
This was the first time someone had sincerely considered his safety like this.
Aizen didn't say much more. He simply nodded.
"I know where Katō lives. I'll take you there now."
Nanatsuki summoned Kagehime, wrapping both of them in shadow.
Although he couldn't fully pull Aizen into the shadow realm to completely hide their forms, he could at least use shadows to cloak them. At night, this method was practically the same as invisibility.
A short while later, the two of them arrived on another street.
This neighborhood wasn't too different from where Aizen lived—wooden shacks lined both sides of the road.
However, this street had clearly been built earlier. The houses on either side were noticeably more dilapidated.
"The people here were mostly born in the Fuwai District," Aizen whispered.
"Most residents on my street are souls that came from the World of the Living."
"There, that's the place," he pointed to a wooden house near the street's edge.
"Katō doesn't seem to be home."
There was no trace of Reiatsu inside.
Katō was never someone good at hiding his spiritual pressure, so Aizen was confident—he wasn't there.
"If he didn't suppress his Reiatsu, we should still be able to track his residual spiritual signature," Nanatsuki said.
He entered the house through a shadow.
The Katori-ryu included numerous exercises for controlling Reiatsu and manipulating Reishi from the environment. Naturally, Nanatsuki also knew how to use Reiatsu Threads for reconnaissance.
He carefully focused on the Reishi in the room. Moments later, the spiritual particles in his senses took on the form of fluttering silk strands.
"Got it." Nanatsuki reached out and grasped one of the threads—white tinged with red.
Human soul threads were white. Shinigami threads were red.
Katō's thread was shifting toward red—clear evidence that he'd already developed some Shinigami traits.
'What determines the color of a spiritual thread?' Nanatsuki pondered.
He suddenly recalled that Quincy threads were also white.
In terms of sheer power, the elite Quincy he'd met were definitely stronger than most Shinigami soldiers.
So the thread's color wasn't based on strength.
'Maybe the emergence of the Zanpakutō causes some kind of transformation in a Shinigami's soul. That would explain why that "Divine Blade", which seems to be a Bakkōtō, is changing Katō's soul as well...' Nanatsuki speculated silently.
He sank back into the shadows and returned to Aizen's side.
"Let's go. I found Katō's location."
He was fairly far off, in a mountain forest—but at their speed, they'd reach it in ten minutes.
By the time they arrived, Katō's Reiatsu had already disappeared.
The area looked chaotic, as if a battle had taken place.
To Nanatsuki's surprise, he found a student from the sixth-year class here.
It was none other than Kan no Ki Homura—the very same student he had punished with detention for misbehavior!
And the sword in his hand was undergoing a violent transformation.
A few minutes earlier—
The forest echoed with the clash of blades.
Including Katō, four boys were locked in a deadly duel with real swords.
The fight didn't last long. It was already nearing its end.
In the end, only Kan no Ki Homura remained standing. The other three lay on the ground—Katō among them.
"I won—hahaha!" Kan no Ki Homura gasped for air. He had finally taken down all three.
He could feel the Divine Blade in his hand constantly absorbing his Reiatsu—but in return, it was feeding him boundless power.
'Who cares if I don't have a Zanpakutō!'
'With this, I'm already stronger than most of my classmates!'
'If I keep nurturing this sacred weapon, I'll only grow stronger!'
Just then, the three boys lying on the ground suddenly let out cries of pain.
"Aaaah!!!"
Kan no Ki Homura turned and saw them desperately trying to throw away their blades.
But the swords seemed glued to their hands—no matter what, they couldn't let go.
Spiritual flames burst from their bodies, and their Reishi forms began to dissolve before his eyes.
Within seconds, all three of them melted into spiritual particles—completely drained by their swords.