A thousand years ago, a group of unprecedented villains emerged in Soul Society. They formed a violent syndicate, which was the precursor to the Gotei 13.
Unohana was one of them.
Before joining the Gotei 13, she was known as the Greatest Villain of Soul Society, addicted to battle, cruel and bloodthirsty. She prided herself on mastering all schools and sword styles in the world, thus naming herself "Yachiru."
In a boring world, only battle could bring Yachiru a modicum of joy.
Just as water is to life, battle was to Yachiru.
But this was far from enough. Brief pleasure was followed by even greater emptiness. She needed stronger opponents.
Then Yachiru met Yamamoto. He was strong, stronger than any opponent she had ever encountered.
She lost, defeated by Yamamoto's endless flames.
Yachiru discovered that the team led by Yamamoto had a goal very similar to hers. So, she joined Yamamoto's group.
To counter external forces, they carried out cruel and brutal operations, crushing all enemies.
Subsequently, the Gotei 13 was formally established, and Yachiru became a core member, serving as the captain of the 11th Division.
She established a standard: the 11th Division, as a combat division, must have the strongest captain in Soul Society, who must defeat the previous captain.
As the originator of this concept, Yachiru earned the title of "First Kenpachi."
To enjoy ultimate combat, she specifically learned Kaido techniques. But after that, the world became boring again.
According to her agreement with Yamamoto, she couldn't attack her so-called comrades.
So, Yachiru went to Rukongai, under the guise of suppressing Rukongai thugs, to find opponents who could bring her joy.
Finally, a brat appeared. He stood atop a mountain of corpses and attacked her.
This man, whose surname was a place name, was a complete monster, who sealed his own power to seek the ultimate pleasure of battle.
Although Zaraki pierced her chest, leaving the only scar on her body, she won after a simple yet intense battle.
This monster had not unleashed his full strength, which greatly disappointed her.
Afterward, she transferred to become the captain of the 4th Division and changed her name to Unohana Retsu, never again experiencing the thrill of battle.
A thousand years passed, and this monster reappeared, even claiming the title of "Kenpachi." But Zaraki had become weaker than before.
Then, Shin appeared. This man grew from an ordinary human to an existence comparable to the Captain-Commander at an unimaginable speed.
He displayed superb healing methods and harbored the same thoughts as her.
Shin somehow learned of her title as "First Kenpachi" and seemed to have intentionally provoked her into battle multiple times, eager to get close to her.
Finally, Unohana's desire for battle, dormant for a thousand years, stirred once more. But even so, when facing the Arrancar named Ulquiorra, she still suppressed her fighting instincts.
In that battle, she merely used Kidō to cope, and eventually, Ichigo "resurrected," freeing her from the fight. This made her both relieved and somewhat disappointed.
Until Shin unleashed an astonishing sword strike in his duel with Aizen.
In Unohana's eyes, that single strike, even after being weakened by two barriers, was enough to destroy a city. This made her unable to suppress her inner desire any longer, and she accepted Shin's request for a spar.
However, in Unohana's dictionary, there were no such words as 'sparring,' only 'slaughter'.
Today, she found Shin and told him her true name.
Her purpose was to tell him that the person standing before him was not Unohana Retsu, the captain of the 4th Division, but the great villain from a thousand years ago—Unohana Yachiru.
Shin successfully wounded her. She couldn't remember how long it had been since she felt pain. This ignited her fighting instinct and made her increasingly excited.
Only continuous slaughter could satisfy her.
The meaning of battle lies in slaughter, and the meaning of learning Kaido is also in slaughter.
Unohana was very curious about Shin's reaction after learning the meaning of this name.
So far, Shin had appeared quite righteous. She wondered if he would eliminate her, the notorious great villain?
...
"Nohara, do you know the meaning of the name Unohana Yachiru?"
Unohana's tone and voice had changed at this moment, completely different from her usual gentleness.
"Yachiru represents my swordsmanship. It is battle, it is slaughter."
"I, Unohana Yachiru, was known as the 'Greatest Criminal' a thousand years ago."
A powerful Reiatsu and terrifying killing intent erupted from Unohana.
'Unohana seems to want to tell me she's not a good person?'
Shin, of course, didn't care about such things. "A criminal? Then I guess I'm a small villain."
"Is that so? Nohara, your actions don't quite align with 'evil'."
"That's not necessarily true."
If those surviving nobles knew that the destruction of the noble district was orchestrated by him, they would surely be happy to bestow upon him the title of "Greatest Criminal."
"Nohara, are you and Aizen the same kind of person?"
Unohana had long sensed Shin's uniqueness but hadn't dared to believe it until he admitted it today.
"Yes, and no."
"It seems you also have quite an ambition. Is it really appropriate to expose it to me, a captain of the Gotei 13?"
Unohana interpreted this as Shin also having ambitions, but judging from his several repulsions of Aizen, he didn't seem to be aligned with him.
"I will not stand against you."
Shin showed a confident smile and continued, "Moreover, I will conquer you with my strength."
"Then... go ahead and try."
Unohana admired Shin's confident demeanor, no one had ever said such words to her before.
Thus, the two clashed again in battle.
Blades met, and bursts of energy shot out, stirring up shattered stones from the ground.
Shin unleashed a giant flame attack. Purely with swordsmanship, he couldn't defeat Unohana.
Unohana actually blocked it with her Zanpakutō, taking the full force of the blow. She then rose into the air, dissipating the force of the attack.
Landing back on the ground, she swung her Zanpakutō, unleashing a slash that split a nearby boulder.
"That's it! Show me all your strength, and let me experience unprecedented joy!"