They pressed deeper into the interior, moving away from Churyo Station.
The stone-paved road eventually broke off, giving way to hard-packed earth. There were no lamps. Only the blue light from Kuon’s prosthetic eye cast a narrow, flickering glow at their feet.
The further they moved from the station, the heavier the air became. A resistance, like walking through water, crawled up from their toes to their waists.
"It’s just ahead."
Kuon narrowed his prosthetic eye. The blue beam probed the darkness ahead, coming to a rest at a single point in the empty space.
There was no door. No wall, no gate, no signpost. And yet, a boundary existed there. Here, even the air’s density changed, as if a thin membrane were stretched across it. The space on this side was fundamentally different from what lay beyond.
Koyoi couldn't see it with his eyes. But he knew exactly where the threshold was because the pulse within his drawstring bag suddenly quickened. Three steps ahead. Shizuku—the drop—was telling him.
"The entrance to the Scripture House," Kuon murmured.
His voice was hoarse. The blue light of his eye wavered unsteadily; the strain of overdriving it in the heart of the shadows had not yet faded.
"The keys are gathered. The three wells’ states are in your hands. But—"
"But?" Asahi took a step forward.
"To open the way, one more thing is required. The 'state' alone is not enough. It needs a living will."
Koyoi looked at Kuon. "A will?"
"The hand that inserts the key. A being that doesn't just hold the record, but touches the boundary of its own volition. The frost, the water, and the mud in our hands are still merely the materials for a key. To become the key, there must be the act of offering."
In that moment, something stirred inside the drawstring bag.
Koyoi felt the cord of the bag slacken. He hadn't loosened it himself; it was being pushed open from the inside.
A single drop—Shizuku—slid out from the mouth of the bag.
It was no longer a tricolored bead. A portion of the sphere had transformed. A rounded head, a short tail. The water droplet had chosen its own shape, taking on a specific form.
A tadpole.
Koyoi caught his breath. "...Otama?"
When he called the name, the shape became a little clearer. The tail gave a small twitch.
Otama flicked itself forward once upon Koyoi’s palm. There was a faint, watery sound. Then, it slid down his fingertips and dropped to the ground.
The moment it touched the earth, Otama began to move. Straight toward the boundary.
"Wait!" Koyoi reached out. "You don't have to push yourself. I'll—"
"Don't stop it," Kuon said quietly. "It has decided for itself."
Koyoi’s hand froze.
Watching Otama move, he understood. It wasn't being driven, nor was it being pulled. It was striking the ground with its own tail, advancing by its own strength.
There was no hesitation in its movements.
Asahi watched in silence, arms crossed. "...The little guy’s made up his mind."
Otama stopped just before the boundary. For a single heartbeat, all motion ceased.
Koyoi bit his lip. He wanted to stop it. He wanted to pull it back and tuck it safely away in the bag. But Otama’s back—that tiny back made of water—was telling him something.
This is where I must go.
Otama had no words. But Koyoi knew that the brief pause wasn't a look back in doubt, but a confirmation. It was checking its own resolve one last time.
Otama touched the boundary.
A sound echoed. It wasn't a bell, nor was it the wind. It was the sound of a single sheet of paper being quietly turned—a page opening, a record waking up.
Otama’s form began to thin. It didn't vanish; it dissolved into the boundary. Like water soaking into the earth, Otama’s shape spread across the membrane of the threshold. From the point where it spread, the quality of the space transformed.
The presence of the "other side" began to bleed through to this one.
"It’s open," Kuon whispered.
The door remained invisible, but a section of the boundary was now passable. Only where Otama had dissolved had the resistance in the air vanished. It was a gap just wide enough for one person to walk through.
Koyoi reached out toward the boundary. He touched the spot where Otama had melted away.
It was warm.
Neither cold nor lukewarm. The same warmth as a living body lingered on the membrane. It was Otama’s temperature.
"He’s not gone," Koyoi’s voice trembled. "Otama is right here. He became the door... he’s right here."
Kuon said nothing. He adjusted the ledger in his arms and faced the boundary.
Asahi went first. Grip still firm on his sheath, he stepped through the space Otama had opened. The moment half his body entered the other side, Asahi’s breath caught for a second. But he immediately pressed on and vanished completely into the beyond.
Kuon followed. The moment the blue light of his prosthetic eye touched the threshold, the light pulsed once, brilliantly, before he passed through.
Koyoi was the last.
He stood before the boundary and placed both hands over the warmth Otama had left behind.
"Thank you."
That was all he said.
The drawstring bag felt lighter now. Lighter by one small life. But the trace of warmth remained. In the place where Otama had been, there was still a lingering heat.
Koyoi let go.
He stepped through the boundary. The air on the other side was heavy and still. It smelled of old paper. The scent of a place where vast, ancient records had been piled high for eons.
Looking back, he saw the membrane of the boundary slowly regaining its thickness. But the spot where Otama had dissolved retained a faint, warm hue. It would not close completely. Not as long as Otama was there.
Koyoi turned forward. Asahi and Kuon were waiting a few paces ahead. In the dark expanse, only the blue light of the prosthetic eye shone like a lone lantern.
Koyoi began to walk toward that light.
Feeling Otama’s warmth at his back.