"What is this?"
Haruto examined the box in his hand for a moment.
He didn't feel any particular pressure about accepting it. After confirming that it wasn't one of Byakuya's pranks, he casually untied the string at the top.
Inside—
A glass bead as clear and elegant as jade rested quietly within. Mist churned and swirled inside it, as though something alive were breathing in that tiny space.
"…"
Even Byakuya paused for a brief moment in surprise. It was his first time seeing what was actually inside the box as well.
"You know about my father's condition, right?"
"Yeah."
Byakuya's father, Kuchiki Sōjun, was currently the Vice-Captain of the Sixth Division.
In both Kidō and swordsmanship, he was considered exceptionally gifted. In front of his father, even Byakuya could hardly be described as a genius.
Unfortunately—
Sōjun's body was frail. Worse even than Captain Jūshirō Ukitake of the Thirteenth Division. A single serious battle would leave him bedridden for a long time.
If not for that, Kuchiki Ginrei would have long since passed both the clan head position and the Captaincy down to him instead of continuing to fight on the front lines at his age.
"My grandfather searched all over Soul Society for ways to treat my father's condition," Byakuya continued.
"The most effective method…"
He pointed at the glass bead in Haruto's hand.
"Was this."
"So what exactly is it?"
Haruto carefully lifted the bead out of the box.
"It's the Tenjōgan, created by the Twelfth Division Captain, Kirio Hikifune."
Kirio Hikifune.
Haruto knew that name very well.
The current Twelfth Division Captain who would later be promoted to the Royal Guard after laying the foundation for the development of artificial souls. The so-called "Grain King," the purple-haired beauty with terrifying culinary abilities.
"Captain Hikifune's greatest ability," Byakuya explained, "is infusing her own spiritual pressure into food in a neutral state. Anyone who eats it experiences a dramatic surge in spiritual pressure."
Even setting aside her work on artificial souls, that ability alone was absurd. While it couldn't raise someone's upper limit, it could push any Shinigami to their personal peak in the shortest time possible.
Of course—
The body had to be able to withstand that sudden surge. Otherwise, the overwhelming spiritual pressure would simply cause the person to explode from within.
And the cost wasn't small either. To create such food, Hikifune had to massively overeat beforehand, storing up enormous reserves of spiritual pressure within her own body.
"To make sure the body could handle that spike in spiritual pressure," Byakuya continued, "Captain Hikifune developed the Tenjōgan."
"I've never heard of it."
"That's because," Byakuya said flatly, "the materials are extremely rare. And since safety couldn't be guaranteed, after producing three trial pieces, the Central 46 classified it as a prohibited item."
"What materials?"
"…"
Byakuya answered with a single word.
"Hollows."
Haruto almost thought he misheard.
"The spiritual fragments of a Vasto Lorde."
Silence fell.
Haruto's shock was genuine this time.
Vasto Lorde were the highest class of Menos. There had never been many of them in Hueco Mundo's history.
Where exactly had Hikifune obtained fragments from one?
"She didn't personally go to Hueco Mundo and kill one, did she?" Haruto asked carefully.
"No," Byakuya shook his head. "I don't know the full details. But my father mentioned it once. It was probably obtained through our clan's channels."
Of course.
Without the backing of the Kuchiki Clan, that kind of research would never have passed through Central 46.
"Right," Haruto muttered. "So does it actually work? Otherwise, something this precious wouldn't have ended up in your hands."
"It works," Byakuya said firmly.
"Just… with some side effects."
"I knew it wouldn't be that simple," Haruto replied dryly.
"After consuming it, the body will continuously absorb spiritual pressure to strengthen muscles and physical structure," Byakuya explained seriously. "The first dose has the strongest effect. After that, absorption decreases. And it can't be stopped by willpower."
"More than one dose is useless."
"That's what my father concluded."
Haruto nodded slowly.
"So in simple terms—my spiritual pressure growth will slow down, but my body will grow stronger by absorbing it?"
"Exactly."
That was precisely why it had helped Sōjun.
Haruto weighed the bead in his hand once more.
"I can use this."
Before Byakuya could react, Haruto tossed the Tenjōgan lightly into the air—
And swallowed it.
"Hey—!"
Byakuya hadn't expected him to act so decisively.
Shinigami valued spiritual pressure above nearly everything else. Most people would hesitate for days before risking something that could interfere with their spiritual growth.
Haruto, however, understood his own weakness clearly.
His spiritual pressure control and growth were excellent.
His body was not.
No matter how much spiritual pressure he had, if his physical durability couldn't keep up, he would always be limited.
If sacrificing part of his spiritual pressure growth meant gaining a stronger body—
That was a trade he was willing to make.
"So?" Byakuya asked.
Haruto flexed his fingers slowly, sensing the internal changes.
"There's an effect. But it's not exactly like what you described."
The strengthening wasn't explosive. It was subtle. A steady redirection of spiritual pressure inward.
Interesting.
"Maybe your spiritual pressure is too weak," Byakuya muttered.
"Or maybe your father's imbalance was just that severe," Haruto shot back.
Byakuya clicked his tongue.
"Anyway, when you finally improve in Zanjutsu, Hakuda, and Shunpo… I might already be a Captain by then."
"Dream on."
Haruto stood up.
"We'll see who becomes Captain first."
After Byakuya left, Haruto remained alone in the underground training chamber.
He extended a finger.
"Hadō #4… Byakurai."
Lightning flashed.
The power output was unchanged.
But the recoil on his muscles—
Reduced by nearly half.
Recovery time—
Cut dramatically.
Haruto narrowed his eyes.
"So that's how it works."
His body was adapting faster than expected.
"Still too weak," he muttered.
His Zanpakutō remained silent. No response. No resonance.
If he couldn't awaken it, his combat power would always be incomplete.
Shunpo and Hakuda would take time.
Zanpakutō… uncertain.
Which left—
His gaze sharpened.
"If I want a rapid increase in combat power…"
He exhaled slowly.
"High-level Hadō above number sixty."
That was the path.