For Unohana Retsu, her Zanpakutō was never the cornerstone of her strength.
Her overall combat ability transcended her Zanpakutō's utility.
While her Shikai, Minazuki, possessed unparalleled healing capabilities rather than offensive power, her Bankai, Minazuki (Bankai)—a corrosive, acidic release paired with blood-like energy—was more suitable for fighting. However, unleashing Bankai in a battle like this, especially an assessment, would be excessive and unnecessary.
So, compared to liberation of her Zanpakutō—
In the countless battles she experienced nearly a millennium ago, she preferred the sealed form of her blade, relying on her peerless kenjutsu—her masterful swordsmanship—to slowly and methodically torture her enemies…to death.
To complement her unparalleled mastery of the sword, she had diligently refined her Shunpo, Kidō, Hakuda, and Zanjutsu. These four fundamental disciplines—Shinigami's core combat arts—were honed by her to the pinnacle. In terms of battle-readiness, Unohana Retsu had achieved an omnipotent state.
As for why she relinquished the title of the First Generation Kenpachi, retreated into Kaidō, and became the captain of the Fourth Division—there was a reason.
She had lost.
Lost to a being stronger than herself.
In that being's eyes, she saw a deeper, more desperate hunger for battle than even her own.
So, to make that person's battles last longer—so they could savor the bloodshed—she studied Kaidō.
Kaidō, the healing art of Kidō.
By mastering Kaidō, she ensured that she would not die easily in combat. More importantly, she could heal that person's wounds mid-fight, allowing them to continue, to suffer, to experience battle more fully.
Ever since she was defeated, Unohana Retsu had been waiting—for that person to return to Seireitei. Waiting for a rematch. A deathmatch.
Yet, in this captain assessment, she had encountered another anomaly.
Gosuke Shigure.
He had not released his Zanpakutō either. Simply using pure Zanjutsu, Shunpo, and basic combat techniques, he was parrying her refined blade strikes—strikes honed through centuries of battle.
It caught her by surprise.
For the first time in ages, during combat, a trace of killing intent seeped from her presence. Keen observers would see her form trembling ever so slightly beneath her medical captain's haori.
It wasn't fear.
It was excitement.
"Gosuke Shigure… Show me your worth."
"Can you entertain me…?"
The words that came from Unohana Retsu—the ever-gentle healer—were chillingly strange, distorted by something primal.
In the next instant, her blade quickened—sharper, faster, deadlier.
She was serious now.
Gosuke Shigure immediately perceived the shift in her demeanor, but his expression didn't change.
He raised his blade, sword pressure rippling forth, and deflected her strike cleanly.
At that moment, when Gosuke Shigure blocked her blow—
Unohana Retsu extended her left hand.
"Hadō No. 4 – Byakurai!" (White Lightning)
A bright white bolt of lightning shot from her fingertips. While one of the most basic Hadō spells, in battle, even the lowest-level Kidō could shift the tide.
The radiant bolt aimed for Gosuke Shigure's eyes, flashing suddenly—brilliant, disorienting.
He instinctively narrowed his gaze.
Unohana took advantage of the opening. Her body flickered using Shunpo, appearing instantly to his side, slashing diagonally from below with sinister precision.
Relying on sheer instinct, Gosuke Shigure intercepted her strike mid-air.
Boom!
Their colliding Reiatsu exploded into raw sword pressure. The shockwave broke apart into residual spirit particles, sweeping through the air, forming a gale-like spiritual storm.
The windstorm surged violently.
From the field's edge, the battle's spectators—Captain-Commander Genryūsai Yamamoto and Division Zero's Hikifune Kirio—watched on. Their haori robes flared in the wind, but they remained unmoved.
Hikifune Kirio's eyes sparkled, revealing her awe.
Though she was no longer among the captains of Gotei 13, her tenure far surpassed many, and she understood the truth about Unohana Retsu.
When a blade hides its edge, it doesn't mean it has dulled. No.
It becomes more dangerous.
Because no one knows when it will strike—or how deep it will cut.
Unohana Retsu was no longer testing Gosuke Shigure.
She was fighting him.
Against such an Unohana, any other candidate would have long since activated Bankai or revealed hidden power.
Yet Gosuke Shigure did not.
He continued fighting with a sealed Zanpakutō, matching Unohana's every blow through his mastery of Zanjutsu and movement techniques.
This was, under normal circumstances, unwise.
Unohana Retsu's strength was not in her Zanpakutō's abilities.
Her real power lay in her full command of the Four Combat Arts—especially her mastery of Zanjutsu.
Her swordsmanship was unmatched in the Soul Society.
Thousands of years ago, with nothing but a blade, she slaughtered foe after foe—monster after monster.
And Gosuke Shigure?
Despite being raised by Takuyashiki and becoming the Eleventh Division's vice-captain, he was still young. No matter how skilled, he could not possess Unohana's brutal, endless experience.
Facing Unohana Retsu in swordplay was like a cub attacking a dragon.
That's what Hikifune Kirio believed—at first.
But now… she realized she had been mistaken.
Gosuke Shigure wasn't being overpowered. He was enduring.
He was parrying, predicting, and countering every motion—not through brute strength, but through combat instinct and honed awareness.
"Still, Captain Unohana has many more cards to play…"
A slight, knowing smile played across Hikifune Kirio's lips.
Call it dishonorable, call it underhanded—but this was Unohana Retsu's way.
Her fighting style, twisted and cruel, mirrored the dark schools of swordsmanship she had mastered across ages.
Her right hand never ceased its relentless assault.
But her left hand—her silent hand—stretched forward again, unnoticed in the chaos.
Previously, she had used Byakurai to blind him.
Now, she activated another Hadō—without an incantation.
"Hadō No. 12 – Fushibi!"
Thin, orange threads of spiritual energy manifested, weaving silently around Gosuke Shigure's position, anchoring into the ground, limiting his retreat.
Though low-level, Kidō like this still had its uses.
Even with the incantation skipped, Unohana's level as a captain ensured the spell had strength comparable to a fully-chanted version from a seated officer.
These threads wouldn't hold Gosuke for long—barely a second, perhaps.
But in combat, one second could decide everything.
A flicker of exasperation appeared in Gosuke Shigure's gaze.
Unohana's blade came for him—merciless, unrelenting.
And in that decisive moment, as he raised his sword once more, his lips moved:
"Kudakero—Raijin no Saigai."
"Destroy—Thunder Tribulation!"