After the rain, dusk arrived, and the night sky sank low.
A faint set of footsteps broke the silence of the mountain forest.
Two figures dressed in white haori appeared at the site of the battle between Katori Nanatsuki and Unohana Retsu.
They took out a set of instruments, collecting the residual Reiatsu in the area.
"Good thing it's Vice-Captain-level or higher. Otherwise, the rain would've washed the traces away," one of them said.
Even the rain in the Soul Society contains Reishi, and ordinary residual Reiatsu can easily be scattered by it.
"If it wasn't Vice-Captain level, we wouldn't have had to come all the way here," the other added.
At that moment, Katori Nanatsuki from Squad Two was sparring with Flash Goddess Yoruichi.
Yoruichi had been busy with missions lately and hadn't visited the dojo much.
Nanatsuki had no classes today. After bidding farewell to Unohana, he didn't leave Seireitei immediately, but instead chose to check on Yoruichi's training progress in Squad Two.
"You've improved quickly, Yoruichi," Nanatsuki said, casually grabbing the leg Yoruichi had just swung toward him, though his expression shifted slightly.
His shadow sight, left in the outskirts of Seireitei, had detected something abnormal.
'Kyōraku Shunsui and Ukitake Jūshirō?' Nanatsuki thought.
Through the shadow vision, he saw two Shinigami in white haori—Kyōraku Shunsui and Ukitake Jūshirō.
Based on what he knew about them, there was no reason they would be collecting Reiatsu data on Katori Nanatsuki.
Which meant… he immediately concluded their true identity—they were Reishi Shells of Kyōraku Shunsui and Ukitake Jūshirō.
"Sensei! Zoning out during a fight is asking for a beating!"
Yoruichi seized the opening. Her body twisted mid-air, her leg slipping free from Nanatsuki's grasp.
Once freed, she lightly tapped the air with her toes and flipped backward, leaping onto Nanatsuki's shoulders.
She landed on them with precision, her legs crossing and bending to tightly lock around his neck.
Then, her upper body dropped backward.
With her hands on the ground and her muscles tightening from waist to legs, she turned herself into a human slingshot, trying to throw Nanatsuki.
But no matter how hard she pulled, Nanatsuki didn't budge an inch.
"Yoruichi, there's a serious problem with this grappling technique," Nanatsuki said, patting her leg to signal her to get down. "Let go."
"Oww, ow ow! Cramp! I pulled too hard and now I can't move!" Yoruichi gasped through clenched teeth.
Nanatsuki had no choice but to reach up and lift her off.
"Let me rest a second!" Yoruichi sat on his shoulders, massaging her thigh.
"Did you notice the flaw in that technique?" Nanatsuki raised a hand and began using Kaido to treat her strained muscle.
"Sensei's Reiatsu is way stronger than mine, so your strength completely overpowers me. That's why I couldn't move you," Yoruichi said after thinking it over.
"Not too dim, at least. Don't use that kind of grappling move in combat again. Master Shunko. If you combine Shunko with your Zanpakutō's ability, it'll help you much more," Nanatsuki advised.
"I got it!" Yoruichi nodded thoughtfully.
"Now that you're healed, get off. You planning to stay up there forever?" Nanatsuki said.
Only then did Yoruichi realize—she was still sitting on her teacher's shoulders.
She quickly uncrossed her legs and jumped down.
"That's enough for today. I'm heading back," Nanatsuki said.
"It's already this late. Sensei's not staying for dinner?" Yoruichi asked.
"No need. I have other things to handle." Nanatsuki bid farewell and left the Squad Two training grounds.
After he left, Yoruichi sat under the eaves, taking a brief rest.
"I sat on Sensei's shoulders for so long just now… He probably doesn't mind, right?" she thought, her face flushing a little at the memory—but thanks to her dusky complexion, it was hard for others to notice.
After leaving Squad Two, Nanatsuki headed straight for the mountain forest where he had previously fought Unohana Retsu.
Shadow sight could only serve for remote surveillance—it couldn't act in his place.
These Reishi Shells looked exactly like the originals, and even their Reiatsu fluctuations were nearly identical.
If not for their behavior today confirming their identity, even meeting them face-to-face later wouldn't reveal whether they were the real ones.
That made this a rare opportunity to catch them.
Nanatsuki merged into the shadows and began moving swiftly through Seireitei via the shadows.
It was his first time entering Seireitei's shadow network since his Reiatsu had improved.
He quickly noticed a difference.
He could faintly sense a peculiar Reishi fluctuation within the shadows of Seireitei.
'The Invisible Empire?!' Nanatsuki's memories of his past life surged forward.
After the Quincy King Yhwach led his army in a failed invasion of Soul Society, he feigned death and went into hiding.
He slumbered within the shadows of Seireitei itself.
Yhwach and the Quincy had constructed a Reishi space within Seireitei's shadows, building an Invisible Empire inside it.
That Reishi space was so well hidden, it had remained undiscovered by the Shinigami for a thousand years.
Now that Nanatsuki could infiltrate the shadows using his abilities, he could vaguely sense the presence of that hidden space.
'My perception inside the shadows has improved significantly,' Nanatsuki noted.
The space inside the shadows had no boundaries, but until now he had only been able to wander near the surface.
With his enhanced ability, he could now descend into the deeper layers.
He tried sinking further in.
After a moment, he found a space in the depths sealed off by a Reishi barrier.
From that barrier, Nanatsuki felt a heavy wave of Reiatsu.
This level of Reiatsu—within all of Soul Society, only Genryūsai Shigekuni Yamamoto's could compare.
The Reiatsu atop that barrier had to belong to Yhwach.
At his current strength, Nanatsuki couldn't force his way past it.
'Once I become a Captain, I'll come back to explore. The surviving Quincy in the Invisible Empire aren't weak. Even if I could get in now, it'd be dangerous,' he thought.
There was still time. Yhwach needed a long slumber to awaken and regain his powers. Nanatsuki didn't need to rush.
This discovery reassured him. Back when he first gained his shadow ability, he had tried searching for the Invisible Empire within Seireitei's shadows, but found nothing, leaving him vaguely anxious about Yhwach's resurrection.
Now that he could confirm its presence, and that he could reach it through his shadow powers, Nanatsuki had gained confidence that he could deal with the Invisible Empire before Yhwach returned.
He rose quickly, returning to the surface layer of the shadows, and continued heading toward the mountain forest.