Minuma Ver. 2 (Reference Map Included)

[Core Room]

"The threat to this dungeon is the Preta. Pretas are dense and cannot swim, so the most effective defense against them is a moat too vast for even a great Preta horde to fill in. In other words, a lake. Granted, a lake in the middle of a desert is the height of extravagance, but fortunately this dungeon produces water in abundance, so we can build a dam and store it up."

"I see."

"Master, having studied the map, I have concluded the following. If we re-route the dry river west of the dungeon, the 'Kamogawa,' to the vicinity of a new Toda Village to be established 40 ri to the southeast, and likewise dam the eastern dry river a little farther east, we can vastly expand Minuma into a large dam-lake whose shores lie close to nearly every post-town. And if we dig a canal along the dungeon's northwest side, the dungeon becomes a full-fledged island, impregnable against the Preta."

Marie projected the map onto the wall, then overlaid the Minuma expansion proposal upon it.

"That's a remarkably long, narrow, branching lake."

"This area is comparatively flat land, so the valleys become the lake. The surface area would be around 8,000 square kilometers, with a maximum length of 400 kilometers. Shallow as it is, the volume should come to roughly three Lake Biwas."

The surface area was three hundred times that of Numata Dam, the volume one hundred times. By otherworld standards it ranked among the larger bodies of water.

"The water's going to pool out quite far, and it'd be a problem if someone went and settled along the shore without leave. Can't we fold it into the dungeon's sphere of influence before the water collects?"

"That would be necessary, yes. If people are already living there, we cannot fold the area into the sphere of influence afterward. It does feel a touch too far, but it will take a considerable number of days for the water to accumulate, so we should have time to spare."

It came to ten years' worth of the Tone River (annual flow of about 9 billion tons), and even six days' worth of the Amazon, so even if surplus dungeon energy were poured in, it could not be filled to the brim quickly.

"Even if we bring it into the sphere of influence, though, we won't have the hands to spare for things like maintaining the roads."

"The library's official cars would run out of charge over such distances. And if we set post-towns along the highways, we will need numerous escort warrior-bands. We can verify images and sound within the dungeon's sphere of influence, but we cannot read people's hearts, so the dungeon's functions alone have their limits when it comes to keeping the peace."

"Ideally we'd place police boxes at regular intervals… It'd practically take summoning the Saitama Prefectural Police."

"That, surely, is out of the question. Furthermore, if we are to build highways, the entire stretch must be folded into the dungeon's sphere of influence beforehand. If the sphere only extends partway, and post-towns not under the dungeon's control spring up along the road beyond it without leave, that will obstruct future expansion."

"In other words, until we've finished widening the sphere of influence and secured additional warrior-bands, the highways stay out of service."

"That would be best. Hiratsuka of the Toshima Magistracy, to the southeast, is 50 ri, but the other three directions are a full 80 ri. That said, to the east there is the town of 'Tanigoe' that the Tsukuba clan built along the way, so for now the sphere of influence can only be widened to about that vicinity. Even so, it is a desert town, dry riverbed alongside it or no. It often happens that such towns are swallowed by the dunes, or their wells run dry. Yes."

"It's not Koshigaya, then."

"This is hardly a Saitama world, after all. This dungeon may correspond in position to Ōmiya, but it is the 'Library-City Dungeon'; like Worker-Peasant Russia, it has no proper name of its own. Translate that country's name literally and you get 'the Union of Council-System Socialist Republics.'"

"And, er, this other dry river one step farther east, what becomes of it? The one before that Tanigoe the Tsukuba built."

"Unless the eastern side is dammed too, the water will not collect, so we cannot reach it yet. That said, there is a fairly broad lowland spreading out near the Nigōhanryō Marshland, so if we dam the downstream end, we could create a body of water several tens of kilometers across. A bit of an overstatement, perhaps, but one could almost call it a sea."

"A sea, at last."

"To properly regulate the salinity would require calculating inflow, outflow, and evaporation, so managing it as a sea would be extraordinarily difficult. Better not to. The sea at Iinuma, on the eastern edge of Sō, is maintained, I believe, by that dungeon's unique law."

"It doesn't have to be a sea, so long as it's sea-like, does it?"

"True enough. Even if it's freshwater, a pure-white coral-sand beach lined with palm trees, Shōnan-style… I would like to say. But are there even palms that grow around here? The climate is moderated near the dungeon's center, yet the summers are still hot and the winters bitter cold."

That said, the sand of the Shōnan coast is volcanic, and so on the blackish side. The beaches of the otherworld's Iwatsuki are Australian sand.

"If the dungeon's range grows wider still, the climate might improve too."