Big post of my SEKAI lore/worldbuilding, which I have written way too much of.
For the past year or so, I've been writing my own lore for how SEKAI works, since I'm not happy with the way it's portrayed in the game and my OCs kinda revolve around it. This is a big post compiling what I have cohesively written down so far, mostly just copy-pasted from my Obsidian. This is inspired by a post of a similar nature about the MLP:FIM magic system lol. It's going to be very disjointed, apologies in advance. Feel free to ask for elaboration 😅
The Dimensional Planes
In this world, there are three dimensional planes:
- The Atomic Plane, where we live. Everything is made of atoms.
1.5: The Virtual Plane, a "layer" of our world filled with code. It helps efficiently transmit emotional energy throughout the Atomic Plane. Not really a true dimensional plane in comparison to the other two... yet.
- The Emotional Plane, where SEKAI denizens live. Everything is made of emotional energy.
That's pretty much all the base knowledge you need. How our world works beyond emotional stuff isn't really relevant, given that we live in it, so let's get right into the Emotional Plane.
Emotional Energy
Whenever a human feels an emotion, Emotional Energy is generated in both worlds. In our world, it's capable of directly manipulating how other people feel. It has to be transmitted intentionally by putting it into the form of music, or by immortalizing it in the Virtual Plane (which we only recently learned how to access). In the Emotional Plane, though, it becomes a physical construct similar in concept to atoms - it forms literally everything.
While (or because?) each emotional fragment carries different concentrations of certain basic core attributes, such as joy or fear, no two fragments are almost ever exactly the same.
SEKAI Formation
Just like in our world, the Emotional Plane contains many universes formed from one major source (in this case, emotions). However, these universes - known as SEKAI - act more like concentrated pocket dimensions, with unique rules for each one.
When first felt, emotions will float across the Space Between aimlessly. However, when it passes by an emotion with similar enough attributes, they will group up. This grouping continues each time a similar emotion is felt, until it is eventually able to take unstable forms for short periods of time. As the process continues, the group will evolve into a Fragment SEKAI; the "infancy" stage of a SEKAI, where the group is stable enough to appear as a tiny pocket universe, but not stable enough to hold this form for long. Many SEKAI permanently stay in the early-mid phases of the Fragment stage, but if enough similar feelings are felt consistently and strongly enough, the group will finally become stable enough to create a fully formed SEKAI. This SEKAI, in turn, can form its own songs from the emotions is carries - and more recently, Secondary VIRTUAL SINGERS.
Because of this grouping system, SEKAI tend to orbit around SEKAI with similar emotions. While incredibly uncommon, if the emotions evolve to be similar enough, two SEKAI can fuse into one. This usually only occurs with Fragment SEKAI and mature SEKAI, though. Last note: People whose emotions heavily contribute to the formation and evolution of a certain SEKAI are known as SEKAI Holders.
VIRTUAL SINGERS oh boy
As mentioned earlier, the two primary transmitters of Emotional Energy in the Atomic Plane are music and the Technological Plane. Music is born from the emotions of the writers, and can directly influence the emotions of whoever listens to it. The Virtual Plane is a constant stream that quickly transmits emotional energy across the world without affecting the emotions of nearby people. When you combine the two, you get VIRTUAL SINGERS: beings born through (not in) the Virtual Plane who carry the emotions found within the songs we have them sing. There are two types of VIRTUAL SINGERS: Primary and Secondary.
Once a voicebank is created, its Primary VS counterpart enters a state of stasis. As soon as the first song is sung with this voicebank, they awaken into the body and (sometimes) personality they were given.
VIRTUAL SINGERS can't generate their own emotional energy, despite being sentient. They feel emotions via "borrowing" them from songs they have sung, therefore, human emotions. The more songs they are made to sing, the wider their range of emotions becomes. And as they become connected to more and more feelings, their chances of Secondary VIRTUAL SINGERS being formed in their image increases, due to them "linking" to SEKAI matching their absorbed Emotional Energy.
With this aforementioned linking comes Secondary VIRTUAL SINGERS. The denizens of SEKAI that form naturally feel emotions in a similar way to VIRTUAL SINGERS, but their emotional energy is absorbed from their SEKAI itself, not music. A Secondary VS is formed when a Primary VS becomes connected enough to the emotions of a certain SEKAI. Secondary VS feel emotions through absorbing both those relevant emotions of their Primary counterparts and the SEKAI itself, making them "hybrids" of sorts. Because their emotional states are directly linked to the state of their SEKAI, they are always acutely aware of any issues that may be happening with their SEKAI Holders.
If a SEKAI is formed from feelings directly relating to a Primary VIRTUAL SINGER (eg. a SEKAI formed from the world's combined view of Hatsune Miku), rather than forming a Secondary VIRTUAL SINGER in their image, the Primary VIRTUAL SINGER will become directly linked to that SEKAI, becoming essentially its Secondary VS equivalent. This is uncommon, though.
Because they were born through the concentrated transmission of emotional energy in the Virtual Plane, VIRTUAL SINGERS can directly enter said plane, which is where the name comes from. They have the ability to access and manipulate code, and even directly possess certain machines, as seen in Nenerobo and Adachi Rei - though this, of course, takes practice. Programming isn't easy.
This is also how the whole Untitled thing works: As mentioned before, SEKAI can form songs in a similar fashion to humans. Things from SEKAI cannot be brought into the Atomic Plane without dissipating and being lost to the Virtual Plane, but if the song is converted into a format compatible with the Virtual Plane - an audio file - it can be used as a "portal" into the Emotional Plane. This is currently the only way to access the Emotional Plane outside of dreams.
That was probably entirely incoherent. Very sorry. But also, that's about all the important stuff! This was actually shorter than I thought it would be. Of course, there's actual history to the world too, but this post isn't about that. Extra notes:
- Strong emotions can affect the electric field, as seen in the movie. In fact, emotions can sometimes be strong enough to break out of their own SEKAI and leak into others... also seen in the movie. The whole movie incident was kind of a massive traumatic disaster that Miku would sell her soul to not have repeated again. It wasn't actually so bad for a lot of secondary Mikus affected, though, as they could at least chat with the other Mikus and learn about other SEKAI until things got sorted out.
- Ghosts exist! They're the "leftover" emotions released when someone dies, and they exist within the Virtual Plane's non-corporeal field (so no, they can't interact with VIRTUAL SINGERS). The closer someone is to their emotions, the better chance they have of being able to see them.