There had been a breakthrough on one of the mountains near Youkai Mountain. Onis looking for metals to dig up and sell, had instead found a type of rock in the ground.
"Slate." said Nitori Kawashiro, Gensokyo Railway's Chief Mechanical Engineer.
"Slate? What are we do with these rocks?" asked Remilia Scarlet, otherwise known as the Scarlet Controller.
"We could mine it, its useful. But we can't extend the railway to where the onis found the slate."
"Isn't there a way to build a smaller railway?"
"Well, we could build a narrow gauge railway. Anywhere between two feet, three inches or two feet. Otherwise, anywhere between 600 and 700 millimeters."
"Where would we get the engines?"
Nitori paused, thinking on what to do. "We could try and build our own engines, but we could overhaul some pre-existing ones just to make things easy."
Yukari was asleep during the meeting and she started to wake up, she yawned and started talking. "What about the Skarloey Railway? Ran and Chen went there and they an engine rescued from an old shed."
"If they found one engine, maybe we could another." said the Scarlet Controller.
"I'm not sure, it might be worth the risk." replied Nitori, "But I'm sure you might find one engine, two if your lucky."
"I'd take that as a challenge." and with those words, Yukari went into one of her gaps and disappeared.
"When should we start construction?" asked Remilia.
"We should figure out the gauge then we'll start immediately." answered Nitori.