Disclaimer: This is entirely theory. While some details are based upon established fanon in the verse, this extended theory is my own creation. Other RPers in the verse are under no obligation to agree to it.
At first glance, the world in which voice synths occupy is relatively simple, especially when compared to other media.
However, the voice synth realm itself has its own set of complications. Songs about being a kitty cat with a wonderful life are just as canon as ones about strapping on your sword to go on a quest to slay an evil witch/dragon to save your sister: in other words, not canon at all, but comprising the entire verse. Songs have become psuedocanon in their own right, essentially an extreme case in which Word of Dante comprises absolutely everything beyond the basic existence of the characters as humanoid-shaped beings with weird hair.
So what do we make of Vocaloid and other voice synths?
The “universe” of voice synths is not entirely unlike a singular universe of the Dragon Ball Z multiverse in that it has different planes of existence. (It can also be thought of as a multiverse and each plane is a universe, but this a stylistic variation and largely unimportant to our discussion.)
Unlike a typical universe, the ‘loid universe has a center, and it is from that center all else expands. This location is the Nexus, and at first glance it is very much the same as the universe we are most familiar with: the solar system is located in the Milky Way Galaxy and Japan is still a crowded island on the third rock from Sol.
Most ‘loids encountered in Twitter roleplay originate from the Nexus. It is here that they sing, buy groceries, fall in love, fall in debt, and fall down the stairs.
However, what is unique about the Nexus is that its occupants are capable of creating entirely new planes of existence through music. While this does not always occur when music is made, in certain circumstances, enough people can imagine the existence of a new realm with such fervor that the realm is created. The origin of the music itself is also a factor; usually, it requires the union of at least one voice synth and a human producer. The reason for this is the same as why humans are ecstatic about making peaceful and meaningful contact with extraterrestrials but aren’t all that concerned with peace with other humans.
The technology in Nexus’s Earth is far more advanced than the typical universe’s Earth regarding robotics, but other than that, it is very similar to the modern day world. The voice synths present on Nexus’ Earth are Vocaloids, UTAU, Voiceroid, Aquastalk, and essentially everything else you can think of, with one notable exception, which we will get into later.
As implied previously, the geography of this Earth is that of our own, as is most everything else. Notably, the majority of occupants on this planet are humans who are familiar with the existence of voice synths. Voice synths with a humanoid appearance tend to be treated like, and live life as, regular humans. Most Vocaloids sing for a living and have lives outside of their work. Other synths may not sing for money (or at all).
For unknown reasons, residents of Nexus’ Earth have relatively high rates of non-heterosexuality. This is extremely noticeable among voice synths.
The Nexus itself has a sort of symmetry in the sense the DC multiverse does. Nexus’ Earth has a planet parallel to it, like how New Genesis is parallel to Apokolips. However, the two are not opposites. The most important difference between Earth and Plogue is that they are at entirely different technological paces because Plogue never went through a dark age. Preservation of life past death was possible as far back as the 19th century.
Chipspeech and Alter/Ego voice synths generally originate from Plogue. However, they may be in different planets within the galaxy containing Plogue.
This plane is one of the many products of the Nexus, perhaps even the quintessential example of the Nexus’ power to create. Evillous has a long, dark, and extensively documented history.
What is unique about this plane is its influence was itself a product of and a modifier of another plane, Hell. In this sense, it can be argued that the man who produced this world (with the help of several Vocaloids) is one of the most powerful people in the entire universe.
where UTAU English reclists originate one of the more mysterious of the realms, as it does not appear to have been created via music with a voice synth and a human. Indeed, it turns out that long-lasting religions and folklore can be sufficiently powerful to give rise to monstrous beings.
While Hell is known for being rather warm, it does not entirely match the Christian tradition surrounding Hell, and is indeed a conglomerate of all sorts of afterlifes of varying degrees of optimism.
Some of the creatures of this land are capable of cross-planar travel of their own devices, although in some instances they are influenced into doing so by the Nexus. Indeed, whether or not any resident of a plane outside the Nexus truly has free will is debatable.
Dante is largely to blame for this.
Neo San Francisco
Given all the LGBT people which exist on Nexus’ Earth, this was inevitable. Lesbians have an easier time living here than other groups owing to their willingness to move in after the first date and having a background in driving trucks which can be applied to U-Haul, saving them a fortune in a place which such high rent.
New visitors are often delighted to learn that the famous Pier 39 sea lions are present here as well. Unfortunately, they are assholes.
Because Plogue lacked a dark ages but kept up some amount of mysticism around demonology (for entertainment as opposed to taking it as seriously as the Puritans), it is debatable Earth’s belief/hope in a God was sufficient to create one. The same goes for a positive afterlife matching heaven. It is possible such a world exists, but most residents of Hell are happy enough to do without it.