Upon returning to Soul Society, all Shinigami who had taken part in the events in the World of the Living were issued an immediate gag order.
No one knew what the Central 46 was thinking. The deaths of several Shinigami had been brushed aside as if they were trivial.
Higashi Shuuichi even heard that Captain Ukitake Jūshirō of the 13th Division had visited Central 46 in person, but the outcome didn't seem ideal. After leaving, Ukitake locked himself in his modest captain's quarters—Rain-Drying Hall—and hadn't emerged since.
A man full of justice, disillusioned by the cold hand of reality.
Shuuichi pitied him. But he wouldn't waste effort trying to change it.
After returning, his daily life resumed its usual rhythm—teaching the 4th Division members about Kidō, Kaidō, and pharmacology; enduring his now-weekly swordsmanship sessions with Captain Unohana, which he half-jokingly called "Her Majesty's Royal Flogging"; giving extra lessons to Kisaragi Shūsuke and Matsumoto Rangiku after school; occasionally serving as sparring partner for Soifon in the 2nd Division; and catching up with Mayuri in the Maggot's Nest, handing over the triangular gem he'd snatched from the battlefield in the World of the Living.
Everything seemed unchanged.
But only Shuuichi knew—after nearly five months of probing—he'd finally managed to coax a few scraps of information from 2nd Division Captain Shihōin Yoruichi about the most mysterious of the Five Great Noble Houses.
The Kōma Clan—tasked solely with overseeing and guarding Hell.
They had no jurisdiction over Soul Society's internal matters, never took part in them. Not even a single member of their lineage had appeared in Central 46. Their presence was akin to the Royal Guard—one existed solely for the Soul King, the other solely for Hell.
And now, with spring in full bloom, Shuuichi paid a visit to the home of the late 10th Division Captain Makizō Kujin in Seireitei.
"I'm terribly sorry for the state of things, Higashi-kun," said the young widow across from him. Slender, modest, the very image of a Yamato nadeshiko.
"No, I'm the one who should apologize. Dropping by unannounced must've caused you trouble."
And he meant it.
After all, he was the one responsible for her husband's death.
Even after years as a captain, Makizō hadn't amassed wealth. He'd been born in Rukongai, married into a low-ranking noble family after his promotion. Barely a year after his passing, his house was already visibly stripped of its former comforts. A hollow shell, echoing with loss.
Some nobles were clearly looking to scavenge what little remained.
After some small talk, Shuuichi explained the purpose of his visit and, with the widow's permission, entered Makizō's private quarters—ones he hadn't been able to search before.
This time, luck smiled upon him.
Inside an old uniform, he found it: a black-marked seal engraved with eerie, twisting runes.
The moment his hand touched it, images flooded his mind.
A shrine cloaked in pitch, candlelight flickering in stale air, shadows bent in lifeless prayer—a place brimming with dread. Malice clung to the vision like mold.
Kōma.
The vision faded, but one detail burned into memory: a hooded figure in the image wore an ornament dangling from their hat, unmistakably matching the crest of the Kōma Clan.
Shuuichi had suspected this since witnessing Makizō's unnatural Bankai and the bizarre spectacle after his death.
In the original timeline, Hell only began interfering with Soul Society after the Thousand-Year Blood War, when countless high-ranking Shinigami perished. The lore stated that spiritually powerful souls couldn't simply return to the cycle—they were cast into Hell, to endure endless punishment and atone for their sins.
Those who bore immense karmic weight would gain power in Hell—becoming "Jūnin"—cursed souls reborn to suffer, battle, and die endlessly.
With so many captains dying in the war, the balance of Hell had tipped. Its prisoners found a chance to break free.
But in this timeline, that hadn't happened yet. Hell shouldn't have emerged.
Which meant one thing:
The Kōma Clan was meddling.
They, who once helped strike down the Soul King centuries ago, had since been charged with managing Hell. Only they had the means—and the motive—to unleash Hell's power.
Clutching the seal, Shuuichi knew he had only one move.
Take the risk.
He had to gamble on the idea that the Kōma Clan, like the Royal Guard, didn't care about Soul Society's affairs—only the domain they guarded.
Only then would everything he'd done until now not get him killed.
Though their silence so far reassured him… when he stepped into their territory, unease twisted his gut.
Because if the Kōma Clan changed their minds, he'd be executed a hundred times over atop the Hill of Dual Punishment.
Silence reigned.
The crunch of leaves underfoot and the sound of his own breath were all he heard.
He pushed open a dust-covered door. No signs of life.
But in his hand, the seal chirped gleefully—like those demonic spirits Makizō had summoned with his Bankai.
Guided by its tug, Shuuichi found a trapdoor and descended.
Dust billowed.
"Hadō #20: Light Sphere."
A glowing orb appeared in his hand, illuminating the stairway. It struck him how absurd it was that this harmless light spell had been classified as Hadō.
Past several empty rooms, he finally found a sealed chamber. The other rooms all contained kneeling skeletons atop tatami mats.
So many pristine bones—in a world where souls turned to reishi upon death. It was unsettling.
He paused before knocking—but then shrugged and pushed the door open.
Even if he had come to ask for help, he wasn't some nobody anymore.
With power surpassing most captains, there was no need to grovel like he did before Aizen.
"You've arrived~"
The voice was that of a girl—clear, delicate, incongruous in such a dead place.
In the room's far corner, a slender back knelt before a shrine.
Pale skin. Frail body. Five blue-faced demons gnawed at her form, driving fangs into flesh, playing with her like food.
If this girl was a member of the exalted Kōma Clan… even Shuuichi, hardened as he was, felt a pang of pity.
"You know who I am?"
He rested one hand on his Zanpakutō, eyes sharp.
"I don't," she said, gazing at the shrine. "But they do."
She meant the demons.
"You've gained their approval. You carry a piece of him. That's why you're here."
Shuuichi narrowed his eyes.
She meant the seal. He'd followed its pull here.
"Is this seal the 'key to Hell'?"
He raised the object.
But no. Makizō would never have carried something that important so carelessly.
The girl shook her head slightly, wincing from the pain.
"No. What you carry is a fragment of that man. You know it doesn't belong to you."
Shuuichi's hand nearly moved to his sword.
The Soul King's nail fragment—one of his deepest secrets—exposed with ease.
"You were waiting for me. Why?"
"Hell is near bursting. If we do nothing, it'll collapse—and bring Soul Society, Hueco Mundo, and the Human World with it."
She seemed more afraid of that than of Shuuichi.
"And what's that got to do with me?"
But he already suspected the answer.
Makizō had been a vessel. And they wanted another.
The girl didn't answer directly.
Instead, she asked, "Do you know what Hell is?"
Shuuichi replied instantly.
"When weak souls die, they become reishi again. But when strong ones die, they can't reincarnate—they get dragged into Hell."
This knowledge wasn't in any textbook. Most Shinigami didn't even know Hell existed.
But he'd walked right into her tempo. The moment she said the word, and he didn't ask for clarification, he'd surrendered the initiative.
Even if he realized it later, it was already too late.
Still, he pressed on.
"Those souls can't die. Some even gain new powers—so they can suffer even more."
Her voice was filled with quiet grief.
"It began with good intentions. But the result…"
"The result," she continued, "is that Hell now overflows. If the sins aren't released, the very system that sustains it will bring ruin."
Shuuichi picked up the thread.
"So your Kōma Clan came up with a plan. Filter the power through a Shinigami's body—release the sins into Soul Society bit by bit. Right?"
The girl's body trembled.
He was right.
It was genius. If raw reiatsu couldn't be decomposed, then use a Shinigami as a funnel. Slowly, steadily dilute it.
But ordinary Shinigami couldn't survive that kind of pressure.
And those who could wouldn't volunteer.
That was how the Kōma Clan had fallen so far.
Those bones in the halls? The price of trying to do it themselves.
Makizō might not have been the first—but Shuuichi was certain he wouldn't be the last.
He would take up the mantle.
"I'll help you."
The room fell silent.
Even the demons paused, puzzled.
The girl had expected a battle of persuasion.
She'd spent days convincing Makizō.
But this one?
Agreed immediately.
"I'll do it. But I want something in return."
She hesitated.
But asked, "Do you know what you're agreeing to?"
"I do. And I know my price."
"If that man's fragment is the key… then I want the lock."
"There's no way you choose victims at random. You need a matching lock to access Hell's doors."
"Give me the lock," he said, voice clear. "I'll carry your dream."
What he wanted… was a ticket to freely enter and leave Hell.
With the Soul King's regenerative power as his safety net, he would brave that domain.
Because he wanted the power within.
The strength of former captains lost to history. The cursed techniques of sinners.
He wanted new teachers.
Aizen's obsession with the Hōgyoku, Unohana's single-minded devotion to swordsmanship—neither could satisfy him anymore.
He needed more.
The girl paused.
Then nodded.
The "lock" was their clan's Zanpakutō—Yomi Basa.
"Hold her. Call her name. She'll open the door."
And as her true wielder, the girl could close it at any time.
She didn't worry Shuuichi might misuse it.
And he didn't ask if she'd trap him.
Because like her…
He offered trust.