Jūshirō Ukitake, Shiba Kaien, and Rukia Kuchiki were all gravely injured.
Yoshio looked up at the now-empty sky and couldn't help grumbling inwardly, "Watch the show and leave, huh? No help at all."
With no choice, Yoshio carried all three back to Seireitei.
"Don't blame me for not using the Kaido; I nearly ran out of reiatsu treating you earlier,"
he told the barely conscious Kaien.
Kaien had been severely wounded twice by Hollow White and was on his last legs. He asked weakly, "Where's the Hollow?"
"It ran," Yoshio said in a low voice. "So you absolutely must not die. If you die, you'll never get your revenge."
Of course, he couldn't say Hollow White had entered Rukia's body—if he did, Rukia would likely be executed.
He wasn't Kurosaki Ichigo; he couldn't shoulder all of Seireitei for Rukia's sake.
And saying "Hollow White escaped" would give Shiba Kaien a goal to strive toward.
He carried the three straight to Fourth Division.
The Fourth Division members were shocked to see them.
Captain Jūshirō Ukitake, Lieutenant Shiba, the Kuchiki family's adopted daughter—all important figures.
"Hurry, mobilize treatment!"
Yoshio was gasping for breath as nearly the entire Fourth Division sprang into action.
"Lieutenant Yoshio, what happened?"
A woman appeared before him. Wearing a white captain's haori, she took the unconscious Ukitake from Yoshio's hands.
She immediately released her zanpakutō, which transformed into a manta ray-like creature that swallowed Ukitake whole.
"It went like this..."
Yoshio recounted the events, omitting of course the part about Hollow White transferring into Rukia.
With Seireitei's current medical tech, such a transfer shouldn't be detectable. If he didn't speak and Aizen didn't speak, no one would know.
And Aizen would surely want to observe Rukia's development next, so he definitely wouldn't talk.
Meanwhile, Yoshio examined Retsu Unohana's soul ability.
["Master of Blade and Heal: The stronger your zanjutsu, the stronger your medical art; the stronger your medical art, the stronger your zanjutsu. The two synchronize; raising one raises the other."]
A strong ability indeed. Fitting for the first Shinigami, the 8th Kenpachi.
But Retsu was even older than Kyōraku; how hard would she be to conquer?
Don't be fooled by fanfics making her the heroine—in reality, an immortal who's lived a thousand years won't be won over so easily. She probably still sees you as a kid in split-crotch pants.
This would be a long and arduous road...
Yoshio gathered his thoughts.
Unohana nodded. "You said you're also proficient in the Kaido?"
"I've only dabbled," Yoshio replied modestly, "and it's very reiatsu-intensive. After treating Lieutenant Shiba and Rukia Kuchiki, I was spent, so in the end I could only watch that strange Hollow escape."
"..."
Unohana said softly, "If you ever want to study the Kaido, you're welcome at Fourth Division anytime. Rare talent—interested in joining us?"
"Captain Retsu, isn't that a bit much?"
Before Yoshio could answer, Aizen's voice came. He arrived just then, pushed up his glasses, and said, "Yoshio-kun is my capable assistant."
"Captain Aizen, why are you here?"
Yoshio asked, 'surprised.'
"I heard my important subordinate was injured. How could I not come?" Aizen said gently. "Yoshio-kun, are you okay?"
"Thanks to Captain Ukitake and Lieutenant Shiba, I'm fine."
Then Yoshio turned to Unohana. "Captain Retsu, since Captain Aizen is here, I'll head out. I'll come see them tomorrow."
Unohana nodded, and Yoshio left with Aizen.
Aizen led Yoshio back to their secret base.
Tōsen Kaname and Ichimaru Gin weren't there. They must have known that a Hollow gravely injuring a Gotei 13 captain and Lieutenant was a big deal, and it wouldn't do for all of them to vanish now.
…
"Incredible..."
In the lab, Aizen allowed a hint of surprise to show as he went straight to the massive central computer.
Layers of prompts and data cascaded across the screen, and finally Rukia Kuchiki appeared on the display.
She was unconscious on a Fourth Division bed, her youthful face breathing faintly; with each rise and fall, the computer displayed new data.
"It's certainly odd," Yoshio said, puzzled. "Hollow White self-destructed—that means it wasn't 'hollowfication' of the target, but the final stage of 'transfer.' That's completely beyond the plan."
"But isn't that more interesting?" Aizen said softly.
"Hollow White chose Rukia Kuchiki as a host, which means something about her drew it. What do you think... that is?"
Yoshio narrowed his eyes. He'd already considered this after switching roles.
Back in his previous life reading Bleach, he'd had this guess; now it seemed right.
He murmured, "The Hōgyoku."
"The Hōgyoku, with an even more particular quality."
Aizen smiled, satisfied, and nodded slightly.
Back when Yoshio read the manga, there were two prevailing views on when Kisuke Urahara put the Hōgyoku into Rukia Kuchiki.
The first, more conventional: Rukia came to the Human World, and then Urahara placed the Hōgyoku into her soul and used his special gigai to hide it permanently.
The second: before Rukia went to the Human World, Urahara had already hidden the Hōgyoku in her soul.
Evidence for the second view came from two lines by Aizen.
["When I learned of this (the Hōgyoku in your soul), you'd already gone missing in the Human World. My intuition told me it was Kisuke Urahara's doing."]
If Urahara had implanted the Hōgyoku after Rukia arrived in the Human World, Aizen wouldn't have said that, nor claimed it was only intuition pointing to Urahara.
Granted, that line alone proves nothing, since Aizen later said much of what he told Ichigo was lies. But the next line matters:
["To verify the Hōgyoku's ability, I sent Kuchiki Rukia to Kurosaki Ichigo!"]