I'm not a good theorist, but I just found something interesting about the songs in their respective chapter.
So, the selection of the songs seems pretty random, no? Well, I think NOT! Apparanetly, some songs represent or depict the Cytus story, or vice versa.
I'll look into every chapter and the most possible number of songs that represent the story.
Chapter 1[]
So we understand from Alive: Operators that scientists wanted to make lifetime memories etrernal through their technoligies, which indicates that they live in a highly modern era. (2130 A.D.)
This is where Visions takes into place. They had visions for such projects and did their best to make it a reality. For some reason, there are gears in the illustration art of Visions. <sarcasm>Oh, I wonder what those represent</sarcasm>.
Then comes Light Up My LOVE and Les Parfums de L'Amour. Looks like Vanessa enjoyed her life with her bae. Heck, you get to even see him in Alive: Vanessa's cutscene.
This one is random. DRG and Secret Garden, both represent gardens. Why's that? And why in this specific chapter? Vanessa enjoyed gardening probably?
Chapter 2[]
The world has gone through a crisis due to a contagious disease. Some songs here represent "disaster", and my first piece of evidence is THIS! Nocturnal Type!
First of all, "nocturnal" refers to an occurance in the night. Hmm...I wonder what occurs at night in a New York-like city with the sirens of police echoing through the area. THAT'S RIGHT! Crimes! Crime is "disaster"!
Next is Precipitation. Wait...I'm not talking about gentle-rain kind of precipation, I'm talking about the heavy ones that causes floods. Now Precipation is a gentle song, but this one represents the gentle drops of rain, while it's hidden counterpart, Precipiation ver.B, obviously represent the up-to-no-good rain. Flood is "disaster"!
I think it's obvious what Entrance refers to. Just look at the artwork: "money money give money". This might indicate that the government was desperate and needed money for medicine. And the music, the music just sums it all.
Chapter 3[]
We understand that Vanessa is in her subconsciousness. Apparnetly the year is 2970 A.D., and to be precise, it was on the 29th of July. Here's the full code:
[29/Jul/2970:12:57:55] OPERATOR 201173V: requesting memory data, name=Vanessa
[29/Jul/2970:12:57:56] OPERATOR 201173V: 200 OK
[29/Jul/2970:12:57:56] OPERATOR 201173V: requesting emotion data, name=Vanessa
[29/Jul/2970:12:57:57] OPERATOR 201173V: ERROR: 501 not implemented
[29/Jul/2970:12:57:57] OPERATOR 201173V: redirect to CYTUS to resolve conflict
We can see that Vanessa was trying to regain her memory and emotions but failed to do so, so the topic here is the "loss of memory". Unfortantaley, I didn't find anything related to loss of memory in any song here. I tried translating COSMO's lyrics but I only got a story about an ark getting wrecked.
Although, I found something interseting in Spectrum. Some of the lyrics translate into: "the signal is repeated, taken by time" "the melody is played in my ears". This matches Vanessa's current situiation. The signal about the error keeps getting repeated every second. And about the "melody played in my ears", this might indicate that Vanessa's quest will consist of her regaining her memory by hearing music.
That's the only thing I could find. If you have anything to support this theory, then please do post it here.
Chapter 4[]
I don't understand the point of the story from here. The only thing we see in Alive: The Silence's cutscene is a bass clef with a whole rest. In music, bass clef is the clef that represent low pitched voices, hence it's low position in the line. A whole rest is an empty space where no notes are played throughout a bar. It's placed at a low area in the line, which represents utter silence.
The first thing I thought of when "silence" came into mind was Landscape, 'cause landscapes are peaceful. Then I remembered Area184. In space, no matter how loud you shout there, you can never, and I mean NEVER hear your voice nor someone can hear it. This is due to the fact that sound waves cannot travel through vacuum.
Another interseting thing I found is in Skuld. Apparentley, Skuld is a character from an old greek mythology (Norse Mythology) which is about a trio of norns (norns are female sorcerers which decide fate). The youngest norn amongst the trio is Skuld, and she's the one that decides who will fight with whom. It is also claimed that she has a horse, just like in the illustration art.
What does this all have to do with this chapter? Norns cause tragic events and associate death, but simultaneously accociate life a birth. This is just a pursuit, because norns, as described in many peoms, are SILENT and shadowy tricksters who remain silent just to hide their evil schemes.
By the way, am the only one who finds a small resemblance between robot Vanessa and Skuld?
Chapter 5[]
In Alive: Vanessa's cutscene, we get to see a glimpse of her dairy which tells that she was skeptical about the tranferring process, mainly because all her family and friends will pass away. We also get to see her boyfriend, maybe even possibly her fiance.
Vanessa is now in stress for losing her closest thing in her life, but she has a task to do, which is recollecting her memory via music. Hmm...recollect...this word appeared somewhere...ah yes, Recollections.
And then we have Biotonic. Here onii-chan's theory will apply, which indicates that Vanessa was taken over by an alternate AI. She was defeated easily by the AI because her emotions towards her family presumabley led to this defeat. But wait...in Chapter 3, the emotion data failed to implement, so what's the most possible reason she was defeated? The AI must've been a very strong one, plus AIs tend to be far more superior than humans in intelligence. This, along with Vanessa's weakness, are the most possible reasons she was taken over easily by an AI.
(please wait for Chapter 6)