Zaraki was powerful.
Logically, a man of such overwhelming might should have long since evolved his Zanpakutō, attaining Shikai even while maintaining a sealed state.
However, for some reason, he sealed himself and suppressed his power.
Coupled with his extremely poor perception of Reiatsu, this prevented him from hearing his own Zanpakutō's voice.
Thus, he had never achieved Shikai. His Zanpakutō remained in a semi-Shikai state for a long time.
Perhaps because of this suppression, his Zanpakutō responded in another way – by manifesting beside him.
That was Kusajishi Yachiru.
She was a little girl Zaraki encountered in the Kusajishi District. Since then, he had taken her in, giving her the deeply significant name "Yachiru."
Before the Thousand-Year Blood War, everything seemed normal.
But when the Quincy Sternritter invaded Soul Society, Zaraki was forced to confront his true nature.
To protect the Gotei 13 and its Captain-Commander role, he sought out Unohana Retsu, requesting that she teach him true swordsmanship – the path of killing he had forgotten since childhood.
Through their life-and-death battle, Zaraki's dormant strength awakened.
The ultimate price was Unohana's death, but Zaraki, having regained his unsealed, most powerful self, finally released his Zanpakutō's true name.
And when he attained Shikai, Kusajishi Yachiru vanished.
If that alone was insufficient proof that Kusajishi Yachiru was Zaraki's Zanpakutō, then the moment Zaraki fell into despair again, her figure reappeared before him, teaching him the method to unlock Bankai.
At that moment, everything became clear.
Kusajishi Yachiru was Zaraki's Zanpakutō, materialised into the physical world.
Why then did Kusajishi Yachiru also carry her own Zanpakutō?
Why could a materialised Zanpakutō wield another Zanpakutō?
In truth, this was not unprecedented.
Consider Kyōraku Shunsui's Zanpakutō, Katen Kyōkotsu.
On the surface, it appeared as a paired dual Zanpakutō, similar to Ukitake Jūshirō's Sōgyo no Kotowari, as if the only dual-wielding Zanpakutō in Soul Society.
But that was not its reality.
Katen Kyōkotsu was originally a single entity. Its secondary blade, Katen Kyōkotsu Karamatsu Shinjū, was created to conceal the true existence of the "Ise Clan's Eight Mirror Sword" hidden within.
If Katen Kyōkotsu could create a secondary form to hide its identity, then Kusajishi Yachiru materialising beside Zaraki and wielding her own Zanpakutō to conceal her nature was not strange at all.
The so-called "Sanpo Kenju" (Three-Step Sword Beast) was likely a power manifested from Zaraki's Zanpakutō upon attaining Bankai.
After achieving Bankai, Zaraki himself took on aspects of a beast, his form partially monstrous.
⸻
Looking at the small girl hiding behind Zaraki, Gosuke Shigure felt a subtle pang in his heart.
"You've given her a good name," he said softly. "So you're ready to adopt her. But… are you sure you want to take in a child?"
Zaraki was momentarily silent. Then he grinned, baring his teeth.
"I've never raised a kid before, but from the moment I saw Yachiru, I knew she could only survive if she stayed by my side."
"If she remained in a place like Kusajishi District, she'd definitely die."
Zaraki wasn't foolish. There were simply things he didn't bother thinking about.
The Zaraki and Kusajishi districts were among Rukongai's most violent, chaotic regions.
He knew this well.
In the past, his strength meant he had no need to care about the chaos around him.
But Yachiru was different.
She was just a child. In a place like that, she could be eaten by starving souls within days.
Though Zaraki had no experience raising children, he knew one thing for certain – Yachiru could only live by staying with him.
He might not provide her with a gentle, peaceful life.
But he could guarantee her survival.
⸻
Gosuke Shigure nodded, understanding.
"I see. If you wish to keep her, I'll handle the adoption paperwork for you."
Under normal circumstances, ordinary Rukongai souls could not enter Seireitei.
Only a few special conditions allowed passage.
One was to defeat the guardians of Seireitei's four great gates – Hakutōmon, Seirōmon, Kōryūmon, and Shōjumon. Defeating a gatekeeper earned their approval to enter, as Seireitei welcomed those of exceptional strength.
This was the method Onirokkujō used to enter Seireitei long ago after challenging Gosuke Shigure.
Another method was marriage to or adoption by a Shinigami.
Of course, the safest path was to become a Shinigami oneself.
Passing the Shin'ō Academy entrance examination granted direct entry into Seireitei as a student, and upon graduation with high marks, one could join the Gotei 13 as a full-fledged Shinigami.
After all, being a Shinigami was a lifelong role. Even in retirement, one remained a Shinigami.
⸻
The reason becoming a Shinigami was the safest way was because Seireitei's spiritual energy density far surpassed Rukongai's.
Ordinary souls who entered Seireitei through adoption or marriage could not endure such an environment, and would wither away within years.
After all, this was the realm of the Shinigami.
But Yachiru was different.
She would not die so easily, because she was not an ordinary soul.
⸻
"By the way," Gosuke Shigure added with an amused tone, "you named her Yachiru… I wonder what Captain Unohana will think when she hears that name. Her expression should be interesting."
Zaraki frowned slightly, puzzled by his words.
He named the little girl Yachiru because the name had instinctively surfaced in his mind upon seeing her.
For the moment, he did not understand why it was connected to Unohana Retsu.