"And during the earlier fight with Aizen, the moment I pierced the 'puppet' he created with Kyoka Suigetsu using Hyorinmaru, I immediately used Ice Double on the spot to create a fake 'Hitsugaya Toshiro', and then my true body hid within the ice walls of the hall."
Toshiro went to some trouble to explain to Unohana why he wasn't dead.
During the earlier battle with Aizen, when Toshiro used his Pseudo-Bankai, the bone-chilling cold aura he emitted had covered the entire hall in a thick layer of ice.
Then, during the fight with Aizen, after piercing the fake Aizen in one strike, he instantly moved next to one of the hall's walls and froze himself into ice as well.
Moreover, the ice Toshiro created this time was special; it could utilize the diffused reflection of light to achieve a kind of 'invisibility', and furthermore, Toshiro's ice could even freeze his own Reiatsu Fluctuations.
Invisible to the naked eye, undetectable by Reiatsu, coupled with the cover provided by the ice crystals ubiquitous in the hall, even Aizen couldn't discover that Toshiro was hidden nearby, and that the one he killed was just a double.
Of course, while this method of hiding was very effective, it wasn't without flaws.
First, regarding the Ice Double itself. Although Toshiro's Ice Double could reach a level of being indistinguishable from the real thing, if an opponent as unfathomable as Aizen were to carefully examine it, he might still be able to detect that the Ice Double was just a double, not the real Toshiro.
Naturally, Toshiro had considered this as well, which is why he timed his confrontation with Aizen to coincide with Unohana's impending arrival.
Then, when Aizen wanted to approach and examine Toshiro's 'corpse', Unohana happened to arrive, forcing Aizen to abandon the idea of a careful inspection.
The second flaw was that while Toshiro was hidden using this method, although it was hard for enemies to find him, it was also very difficult for Toshiro to use this method to sneak attack the enemy.
To launch a surprise attack, Toshiro would first have to break out of the ice, and then attack the enemy. If it were someone else, it might be fine, but against an opponent of Aizen's caliber, the moment Toshiro broke free from the ice, Aizen would become alert and prepare to defend himself.
In that case, Toshiro's attack would lose its element of surprise and become just an ordinary attack. That's why Toshiro had all along stayed hidden, not rashly launching a reckless surprise attack on Aizen.
After listening to Toshiro's explanation, Unohana, although understanding why Toshiro wasn't dead, still had some doubts: "Captain Hitsugaya, since you were fine earlier, why did you go out of your way to hide nearby, letting Aizen believe he had killed you? And why didn't you stop him when he left just now?"
"Ah... well, this... it's a long story. There's no time to explain the details now. In short, just know that the reason I went to all this trouble was to deal with Aizen."
Toshiro said.
"I see... very well."
Unohana didn't probe further. Now was indeed not the time for slow explanations.
"Then, Captain Unohana, now that you generally understand the situation regarding Aizen, you should also know that the accusations of murdering 'Aizen', intending to destroy the Seireitei, and betraying the Soul Society were all slander against me by Ichimaru Gin. So, my positions as Vice-Captain-Commander of the Gotei 13 and Captain of the 10th Division should still count, right?"
Toshiro asked.
Unohana nodded solemnly: "Of course, Captain Hitsugaya."
"In that case, after you convey the message to everyone, please immediately rush to the Sokyoku Hill and join the battle to encircle and destroy Aizen!"
Toshiro said in a commanding tone.
"Yes, Vice-Captain-Commander-dono."
Unohana nodded in acknowledgment, also adopting a businesslike manner.
"Of course, regarding my situation, for now, please temporarily treat me as if I have been killed by Aizen. Do not let Aizen sense anything unusual."
Toshiro added.
"Mm, I understand."
Unohana replied, then looked towards Isane, who had been standing dazedly nearby ever since Toshiro suddenly 'came back to life' a moment ago.
"Isane, you should know how to notify everyone, right?"
Unohana asked.
"Ah! Yes!"
Isane hastily responded, then once again began to use her Kido.
"Silken net of black and white! Twenty-two bridges, sixty-six crowning sash; footprints, distant thunder, pointed peaks, revolving grounds, nightly prostrations, sea of clouds, the pale ranks of troops, complete the grand circle and surpass the heavens—"
"Bakudo #77, Tenteikura!!"
Boom!
Cerulean blue Reiatsu spread through the air like a spider's web.
"Successful!"
At the same time, important figures such as the Captains and Lieutenants within the Soul Society also sensed Isane's Tenteikura, involuntarily pausing their respective actions to listen carefully.
Isane took a deep breath and said: "To all Captains, Lieutenants, and acting Lieutenants of the Gotei 13, as well as the various Ryoka. I am Isane, Lieutenant of the 4th Division."
"Can everyone hear my voice? The situation is urgent. Below is an emergency message from myself and Captain Unohana of the 4th Division."
"Please pay attention. What I am about to say is the truth..."
"Captain Aizen Sosuke of the 5th Division is not dead, and..."
"As for the Vice-Captain-Commander of the Gotei 13, Captain Hitsugaya Toshiro of the 10th Division..." Saying this, Isane couldn't help but glance at Toshiro, then continued: "...has been killed by Aizen Sosuke!"
Within the Seireitei, Eastern District.
Rangiku had originally been leading a patrol, maintaining order amidst the chaos, and helping to capture the Ryoka.
With Toshiro absent and Momo confined in the 1st Division, Rangiku was the only one left in the 10th Division to take charge.
But now...
"Wha... what?"
"The Captain... is dead?"
Thud!
Rangiku seemed to lose all her strength in an instant, collapsing to her knees.
"How... how can this be? The Captain is the strongest, the most genius Shinigami! How could he die?"
Drip, drop, drip, drop...
Tears involuntarily slid down from Rangiku's eyes, shattering on the ground like crystals...
"No way..."
"Toshiro is dead!"
"And killed by Aizen!!"
On the battlefield of Yamamoto, Kyoraku, and Ukitake, Ukitake stood stunned in place, a look of disbelief on his face as he murmured to himself.
Kyoraku picked up his straw hat, which had fallen to the ground during the fight, dusted it off, and put it back on.
"Hey!!! Old Man Yama, stop this. We shouldn't be fighting anymore. Now, I'm going to avenge Toshiro… and kill Aizen!!"
Kyoraku's expression was gloomy, a far cry from his usual lazy demeanor, almost looking grim.
"Yes, indeed, we should no longer be fighting."
Yamamoto said in a deep voice.
However, his expression was calm. He did not show anger or sadness like Kyoraku, as if he didn't particularly care about 'Toshiro's death' or the betrayal of Aizen and the others.