The eponymous supra-city of Yume is split in two sections, the Nimbus which rings the canopy of the world tree, and Ne-no-Mori which straddles the lower trunks. Ne-no-Mori also descends far down into the rising waters, the city itself climbing up the tree over thousands of years, always a hundred or so meters from the primary truck, cordoned off by those that call Nimbus home. Ne-no-Mori is massive, its population being around 5 billion people, while the Nimbus holds, maybe, four million. The two sections of the city have very little contact, though functionally they’re connected via a system of huge wired cables that transfer energy from Nimbus down to the city proper.
The majority of those who live in Nimbus live oblivious to the fact that the people of the Lower City suffer, and those that are aware usually put it down to Dwellers living unholy or unproductive lives. All their focus, devotion and loyalty goes towards the life of Nimbus and what they perceive as their divine mandate, that of appropriately distributing the light of Shinju to the rest of the world.
Many people in Ne-no-Mori, Dwellers, are known to devote themselves to the worship of Nimbus and the energy she provides to keep the city alive and safe from the outer demons.
“Too many of the younger folk don’t understand our history. It’s thanks to Nimbus that the colossi, offspring of Leviathan, are kept at bay! We ignore Nimbus at our own peril!” — Midoria, Data Analyst in the 62nd level of the 1st quadrant in Hoshizato
Although many Dwellers are known to worship Nimbus, a good amount of the city despise those that live “up on high” and the heavy hand that they have over all the “normal people”.
Over the thousands of years of its history, the Yumians have created large energy cables that run from Nimbus down into Ne-no-Mori. In this way Nimbus acts as kind of conduit, transferring the energy collected from Shinju and moving it down into the city.
“The truth is, we don’t even need Nimbus! Shinju has always been able to provide the energy and protection to all people in Yume. Nibus just takes the credit, and they keep this information from us, trapping us in slavery to their whims!” — Khaiyo, missing data, unknown location
Flooding
The very bottom sections of Ne-no-Mori of Yume are greatly effect by daily flooding. These waters, which start to rise once Yume connects to the Kōkai (Day), and thus connects with Leviathan, cover the city at a height of 80 meters at its height at the end of “Summer”, and then receding during “Spring”. This means that these waters move around 13 meters, up and then down, per hour (about the height of a 4 story building).
Additionally, the city loses around a meter to these waters per year, as, on the whole, the waters have risen throughout the last 2000 years, covering 2km of now underwater city.