The moment the train slid into the town at the foot of the mountain, my body felt weightless for a heartbeat.
Even though we had come to a stop, the feeling under my feet wouldn’t stabilize. Looking out the door, I saw rows of houses hanging upside down.
Roofs were below; wells above. The sky stretched out beneath the cobblestones.
"An upside-down town..." Koyoi murmured.
Asahi gripped the edge of the door frame to steady himself. "It’s not just the look of it. Gravity itself is inverted."
Kuon opened his Catalogue, pressing his hand against the pages. The paper didn't flutter upward; it dangled toward the ground outside.
"The gravitational pull switches once you cross the centerline," Kuon explained. "If you trip at the boundary, you’ll be yanked from both sides. It’ll tear you right in two."
The three of them tied their sashes together to serve as a rope, looping them around their waists. Asahi took the lead, Koyoi the middle, and Kuon brought up the rear.
They took their first step into the town. For the first ten paces, everything felt normal. On the eleventh step, their bodies were suddenly yanked upward.
Koyoi’s vision flipped, and her stomach lurched with the sudden shift. But the sash went taut, bracing her and preventing a fall.
"Keep your breathing in sync!"
Following Asahi’s voice, the three walked in a shared rhythm. Even on an inverted alleyway, matching their strides kept the swaying to a minimum.
From the windows of the houses, upside-down residents watched them pass. Their hair dangled upward, while steam fell toward the ground. It was a bizarre sight, yet none of the locals seemed surprised.
"In this town, this is what’s normal," Koyoi noted.
Kuon nodded. "The direction of gravity becomes a culture. It’s not a matter of right or wrong."
In the center of the alley sat a round well. The surface of the water alone belonged to neither up nor down, holding perfectly level in midair. That was the centerline.
Asahi lightly tapped the water's surface with the flat of his sword. The ripples didn't spread in circles; they stretched into ellipses that split upward and downward.
"Dual gravity, just as I thought. Once we cross this, we’re at the exit."
Koyoi clutched her drawstring pouch and stood at the edge of the well. Her pulse was fast, but steady. She could do this.
"On 'three,' we cross."
They stepped out simultaneously. For a fleeting second, their bodies hung suspended in the air. In the next breath, gravity flipped back, and the soles of their feet returned to being right-side up.
Their knees creaked from the impact of the landing, but they stayed upright.
Looking back, the upside-down town was quietly receding into the distance. One of the residents waved "upward" toward them. Koyoi waved back.
"It was strange, but it wasn't a bad town," Asahi said with a grin.
"As long as they aren't enemies, most places aren't bad," Kuon replied curtly. "The real problem is what comes next. In the Mirror Sector, the echoes of the inversion will be hunting us."
The train whistle blew, and the three climbed back aboard.
Checking to make sure her feet were firmly planted on the floor, Koyoi took a deep breath. Beyond the inverted gravity, a new kind of distortion was waiting.
As the train headed back toward the station, Koyoi didn't untie the knot in her sash.
Asahi tilted his head. "Gravity is back to normal, you know."
"I know. But a boundary might appear out of nowhere again, just like before."
Kuon gave a faint smile. "One can never be too cautious—especially right after passing through an inversion zone."
Koyoi looked at the knot around her wrist. A red mark remained where it had rubbed against her skin. That lingering ache was proof that all three of them had held their ground together. Until that mark faded, she knew she wouldn't forget today's town.
What the three prioritized in this leg of the journey wasn't a hurried advance, but the addition of proper safety procedures. Kuon had clearly demarcated the "known" and "unknown" zones from the very first move.
After sharing their findings, Koyoi recorded the details in her ledger.
The more severe the crisis, the more stability depends on clarifying the first move.