It began with a vision.
Not a dream, not a memory, but something rawer—like a scream echoing across time.
Sayo awoke gasping, drenched in sweat, her fingers curled around the blade-shaped charm that had appeared in her palm the night before. The Book of Remnants shimmered faintly on the desk across the room, its sixth space glowing crimson.
Ren sat up, instantly alert. "You saw it too."
Sayo nodded, breathless. "A temple. Fire. Someone was calling my name… and then—"
"I stabbed someone," Ren finished, his voice barely a whisper. "I saw myself holding the knife."
They stared at each other in silence.
"What did Izanami say?" he asked finally.
Sayo looked away. "That the next fragment lies in blood. In betrayal. In the life I ended too soon."
---
That morning, they took the first train to Mount Osore.
The journey was long—northbound across Honshu, through whispering forests and past rusting fishing towns. Mount Osore, the so-called "Gate to the Underworld," lay cloaked in sulfur mist and shadowed legend. It was said that the souls of the dead could be heard on the lake's edge.
As the train wound its way toward the mountains, the Book of Remnants began to heat in Sayo's bag. The blade charm pulsed steadily.
"I think we're going to see more than just echoes," she said quietly.
Ren looked grim. "I think we're going to see ourselves."
---
The town near Mount Osore was quiet, almost abandoned. Only the temple grounds showed signs of life—elderly pilgrims, blind mediums known as itako, and a handful of monks tending to cracked statues of Jizō, the guardian of children's souls.
One of the itako approached them.
"You carry pieces of yourselves," she said, without introduction. "Lives unburied. You must offer blood to pass."
She handed them each a rusted ceremonial dagger.
Sayo flinched.
Ren accepted his silently.
They followed the path to Lake Usori, where the air grew cold and heavy. The trees whispered, not with wind, but with memory.
At the shore, they knelt.
Both pressed the blades to their palms.
When the first drop of blood hit the lake, the world broke open.
---
The vision swallowed them whole.
Sayo stood in another life.
The sky overhead was dark with ash. Smoke rose from burning huts, and screams echoed down narrow mountain paths.
She looked down.
Her hands were soaked in blood.
In front of her, a man lay dying.
Ren.
But not the Ren she knew. This Ren wore a samurai's armor, black and gold, his hair tied back, his face older, crueler.
He gasped. "Why?"
Sayo knelt beside him. Her voice trembled with pain. "Because you killed them. You betrayed the oath."
"They were spies," he hissed. "I did what I had to."
"No," she whispered. "You did what he ordered."
A shadow fell across them.
Another figure approached—tall, imposing, dressed in the robes of a war priest. His face was hidden, but Sayo knew his name:
Takeshiro.
Her father in that life.
He had raised her to be a shrine maiden. A keeper of sacred fire. He had also ordered the deaths of dozens—accused of treason, of heresy, of standing in the way of his rising influence.
Ren had carried out those orders.
Until he questioned them.
Until she found out.
And killed him to stop it.
---
The memory shattered.
Sayo screamed as she staggered back into the present, collapsing on the lake shore. Ren caught her just before she hit the stones.
"I saw it," he whispered. "I remember now."
"You were the executioner," she said. "And I…"
"Killed me," he finished.
They were both shaking.
"But I loved you," Sayo said. "Even then."
Ren nodded. "I never stopped. Even as I died, I thought… 'at least it's her.'"
Tears streamed down her face.
The Book of Remnants flew open.
The sixth fragment rose—this one shaped like a flame, wrapped in blood-red silk.
It hovered before them.
And then dissolved into light.
---
That night, they camped near the base of the mountain.
Neither could sleep.
"I don't know if I can keep doing this," Sayo admitted. "Every time we remember… it gets worse."
Ren looked into the fire. "Maybe it has to get worse before it gets better."
She was silent.
He continued, "What if this is the only way we can finally break the cycle? Not just remembering—but understanding it. Accepting it."
She turned toward him. "Even if the truth is unbearable?"
He met her gaze. "Especially then."
---
As the fire died down, the air around them grew still.
Then the Book opened itself.
On its own.
A new fragment glimmered into view.
This one was different—etched with two names:
Ren.
Sayo.
And between them, a single kanji: Tsumi — Sin.
"Izanami's warning," Sayo whispered. "This is the life where we destroyed everything."
Ren's face was pale.
"But we haven't seen that life yet."
Sayo closed the book gently.
"We will."
The flames stirred.
Somewhere beyond the mist, a crane cried.