"I once met a Shinigami captain named Muguruma Kensei."
"Among the captains, both in terms of raw Reiatsu and overall strength, he should be considered one of the weaker ones. Of course, not weak by normal standards—but among captains, his Reiatsu doesn't stand out."
"So, I use him as the base unit for measuring Reiatsu."
Noticing the brief flash of confusion in Aizen's normally composed eyes, Akira explained casually, despite rarely needing to elaborate before such an astute mind.
"This unit of measurement is practical. It's vivid, intuitive, and comparative. One 'Kensei' equals the Reiatsu output of Captain Muguruma."
"Haha…" Aizen's lips curled into a faint smile.
"As expected of you. You actually used a captain's name—no, his entire being—as a metric unit for spiritual power."
Yet, seeing the logic in it, Aizen adopted the measure without further question.
"According to your definition," Aizen mused, "my plateau period—the threshold at which my Reiatsu stops exponential growth—would begin around 60 'Kenseis.'"
Akira nodded.
He knew the term was crude, but it served its purpose.
Quantifying spiritual growth was impossible in the rigid framework of Soul Society. But to someone like him—who came from another world, or perhaps just another line of logic—such abstraction was a necessity.
"What are you planning to do next?" Akira asked, his tone laced with genuine curiosity.
Ever since his presence altered the trajectory of events, Aizen's entire approach had shifted.
Unlike in the original history, where Aizen meticulously concealed his talents behind a mask of politeness and mediocrity, now he was being more overt—demonstrating his genius openly while still hiding the full scope of his power behind a veil of gentleness.
It was a dangerous charm.
"Since we know that a boundary exists—between Shinigami and Hollow," Aizen said, "I want to explore what happens when that boundary is deliberately broken."
"What if we pour Hollow essence into a Shinigami's soul?"
"Conversely, what if we infuse a Hollow's spirit body with the spiritual structure of a Shinigami?"
Aizen smiled slightly as he spoke, but the implications in his words sent chills down even Akira's spine.
"The experimental results from average Shinigami are meaningless," he continued. "Their spiritual resilience, potential, and Reiatsu ceiling are too low to generate valid data."
"So for that," Aizen said with casual cruelty, "we'll need Captain Hirako's cooperation."
"If he can contribute to an experiment that could break and redefine the upper limits of the Shinigami species, I'm sure he'd be… honored."
The glint in Aizen's eyes said otherwise.
"And before that?" Akira asked.
"We need to go somewhere," Aizen replied.
He didn't need to say more.
"Hueco Mundo," Akira stated flatly.
"Yes," Aizen nodded. "The Hollows invading from the Menos Forest don't suffice. Most are mindless Gillians or barely stable Adjuchas. Their spirit structures are too unstable for structured experimentation."
"Hueco Mundo offers more. It's lawless, filled with evolved Hollows, and more importantly—it's where the Espada dwell. Specimens like them, especially Tier Harribel or Grimmjow, are on par with captains."
"We'll need a base there—a stronghold for research, and a fallback point should Seireitei become hostile."
Akira folded his arms, eyes narrowing.
"Pitiful. Even death is a luxury."
He wasn't speaking out of sympathy. Just a detached observation.
From the moment Hirako Shinji confronted Aizen in public and mocked him—calling him a "bad seed since the womb"—his fate had been sealed.
Hirako hadn't realized that behind Aizen's soft-spoken manners and unreadable eyes hid a mind that played chess with living beings.
Not only Shinji.
The other captains and vice-captains who were friendly with him—Love Aikawa, Rōjūrō Ōtoribashi, Hiyori Sarugaki—they would all be marked by Aizen for their loyalty and their loose lips.
And once marked, death was the kindest option.
After all, wasn't it well-known? Aizen Sōsuke, the seemingly tolerant and kind-hearted officer, treated subordinates like pieces in a complex strategy game.
Not even his "allies" were exempt.
Let alone adversaries like Hirako.
While Akira and Aizen laughed and quietly sketched out Hirako's future—along with that of half the Gotei 13—the other side of the story unfolded.
After leaving Zanjutsu Hall, Hirako Shinji winced and glanced down at the wound on his shoulder.
It wasn't just pain—it was the foreign Reiatsu lingering in the gash.
Akira's Reiatsu, to be precise.
Damn Aizen, he cursed mentally.
Yes, it was Akira who had slashed him and pinned him to the wall. But Hirako's instincts screamed that Aizen was at the heart of it all.
He didn't return to the 5th Division.
Instead, he turned toward the 4th Division barracks.
The Reiatsu left in his wound felt alien—like it was trying to communicate or imprint something into his soul.
It was unnerving.
And though Hirako preferred to avoid her, he had no choice but to seek help from Captain Unohana Retsu.
As he entered the 4th Division, he called out.
"Sister Hua! I've come to visit you!"
But the moment he stepped through the door, he was shoved aside by Unohana with surprising strength.
"Captain Hirako?" she said politely. "Please wait to the side. I'm busy."
Her tone remained warm, but her eyes were focused on the patient in front of her—Lieutenant Sentarō Kotsubaki, who lay unconscious from sparring wounds.
"Sister Hua, I am a captain," Hirako huffed. "Shouldn't I get some special treatment? Like skipping the line?"
He grinned playfully.
Unohana turned to him slowly, her serene smile not wavering.
"What did you say?"
Nothing changed in her expression, but Hirako's spine turned cold.
"No, no, nothing!" he said, hastily sitting down in a corner. "Take your time. I'm just… observing."
Though he liked to joke, Hirako wasn't stupid.
He knew full well what kind of monster Unohana Retsu truly was beneath that gentle mask—the same Unohana who once held the name Yachiru, the original Kenpachi, a berserker of death who had been rebranded as a healer.
She only stopped her killing ways because Yamamoto forced the shift when the Gotei 13 changed from a death squad into a peacekeeping force.
But the bloodlust hadn't vanished—it was merely resting.
After nearly 40 minutes of pretending to look busy, Unohana suddenly turned to him.
"Your injury…" she said, gently lifting his sleeve.
"This Reiatsu wasn't left by a captain's blade."
Her fingers brushed against the wound.
It wasn't just energy—it carried technique. Weight. Precision. Almost surgical.
Unohana's eyes shimmered as something stirred deep inside her.
Excitement.
Longing.
"A captain didn't do this," she said softly. "Who did?"
Hirako coughed.
"Shouldn't a healer focus on treating patients first?" he deflected.
Unohana said nothing. She merely stared at him.
Hirako flinched as her right hand subtly slid toward the hilt of her Zanpakutō.
"Okay! Fine!" he said quickly. "It wasn't a captain. It was someone named Akira—a first-year at the Academy!"
Unohana froze.
Then she smiled.
But to Hirako, that smile felt like the blade of Minazuki drawing blood before it even left the sheath.