I've decided to compile some of my observations concerning Monochroids that COULD potentially hint at something in the near future
Chapter I: Speculation on to who activated Monochroids
At first, I thought Monos were activated by Suzumi before leaving to search for Tsuba and I think it is like the most obvious conclusion to go to; however, with the findings made by Yike (shout-outs to the goat), and something that I myself can confirm - I believe that Monos are actually activated by Tsurubami
Rei-kun refers to their creators, Tsubakura and Suzumi, with honorific "-sama". However as it was noted in the wiki, Tsurubami is the only other character who is referred to as "-sama" - and they also accidentally said "go/ご", which might be a part of "ご主人様" - aka master. Given that if we're going to think that Tsurubami is the person who has activated Monos - it makes sense why Rei-kun currently thinks Tsurubami as their master - as they're the current user/exploiter of Monochroids.
Not only that, there are also signs of tampering (with Rei-kun).
Clothes are the most obvious thing as their clothing looks pretty traditional, which is quite unusual not only because those were provided by their "master", but also because overall outsider characters don't look traditional - wearing blouses as opposed hakamas (with exception of Yabusame, but I suppose it's more of a Yabusame thing)
There's a question of Zelo-chan and NiLU since they don't look traditional as well - but remember: Rei-kun was pretty much abandoned early on, they might not even have clothes at all when they were first discovered (besides their hat I think, on it we do have a camera and a flash, suggesting some kind of espionage? But it could be for recognition reasons).
However there are more subtle ones. When Rei-kun gets asked a question that is "forbidden", they get a protection error.
The formatting of such an error is quite intricate, something that you might face when programming, that ends with a comment "Hmm~, Rei-kun doesn't really know~" However, there's also an omitted version of it that just shows that comment. It would be easy to think of it as a mere variation, but it was noted that it happened on TWO (well, not really) occasions:
1. When Rei-kun was asked to elaborate on Xeno a's relationship with them as they did refer to them as their "buddy" (because while Xeno a is an outsider, it was never implied that our outsider group even knows about them)
2. When Rei-kun was asked to elaborate on Tsurubami's life in the outside world
Xeno a as we know is a buddy-buddy with Tsurubami, and I suppose the reason why Rei-kun can't say about their life is because Tsurubami doesn't want to have their image of a powerful dictator crumble to the ground. I think the reason why the error messages were omitted on that front is because Tsurubami tampered with their code to enforce new censorship, and because they deemed long "programming error" formatting too unnecessary
There's also an issue of bird's eyes. At first I thought it was just Tsubakura working with some sort of "energy provider" and it's their way of naming those eyes: however knowing Tsurubami's ability - it actually makes sense for them to give those eyes to Monochroids and thus releasing their potential energy (ha got'em). And it already happens with "???" race units as before they were just some random tools, but now they have the potential to become something much more greater (while not being Tsukumogami who have to age 100 years to even gain life, again they're listed as "???" Race, not "Youkai")
With Rei-kun, they were already quite unfinished, yet required less energy, thus they have only one eye. Zelo-chan however is explicitly stated to be a living weapon, which is already energy consuming - so they have two eyes. And NiLU seems to be more of a trooper character with their attire resembling a regular soldier so maybe they have one eye? Let's wait and see their reveal (eventually)
And given that they're "Goodwill Ambassador of Mugenri", and while Tsubakura did know about the "other world" it's not like they knew its name (having to clarify the name when they were isekai'd by Tsuru)... Gee, that bastard is trying to propagandise Mugenri to the entire world.
And I think that's all for Rei-kun specifically. For Zelo-chan I can't really say much since they don't really speak much and serve more as a companion to Rei-kun...
HO-WE-VER! NiLU refers to Tsurubami as "Tsurubami-san" and Tsurubami is THE ONLY CHARACTER THAT NILU REFERS TO WITH PREFIX (and "-san" is quite respectable prefix too symbolising superiority). They don't use it even on their own deadbeat creator ffs. And their speech has a more softer/nervous feel, not something that is present throughout the game. Sure it's got debunked with the release of Main story mode, but I would argue that Main Story happens before the back issues chronologically; NiLU here is more courteous with Doc Yabusame and Kurohebi (using -hakase and -san respectively) and curious - while in Back Issue they're more curt. Perhaps they're more or less accustomed to the reality of their situation
Plus Tom looks like that "flying snake thing" midboss that was cut with their batty wings and a tail... But given what we saw in MW trailer, it's very debatable; but again, that "snake" didn't have any Bird Eye motif and if you believe what I said about other bird eyes, perhaps Tom is pure energy.
And now onto "NiLU is somehow connected to Shitodos" theory...
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Chapter II: Possible Correlations with Shitodo Siblings?
Obviously, since we have Suzumi as the third protag, naturally it's logical to think that NiLU is based on them, however Tom started acting... Weird, saying that the answer lies in their heart as to why Kuroji is abiliti-less. So let's draw the comparisons
1. The belts, as they correspond to the Shitodo siblings colours (barring Kuroji, but they were always purple). There's also a point to be made with White belt being separate and way higher from the other three, which is pretty much Shitodo dynamic 101
2. The collar being the trademark black with white lining. Of course it could be me farfetching it, but we have Hoojiro, be it her pre- and post- redesign has a drastically different way of styling her collar (could be distancing from Shitodo siblings); hell, her blouse is pretty much THE biggest hint of her connection to Shitodo siblings
3. The attire and general genre of the game. Kuroji is a military strategist; NiLU, judging by their attire, is more of a soldier (i.e. the one who follows the orders), as their design seems to be inspired by Japanese' WW2 soldier outfit (the hat and puttees) + rain cape to conceal the body. Plus well, BotC is a strategy game
4. One of the key words shown in the opening was "Think" spelled with the same Kanji as Kuroji's hat in EE. That's also far-fetched, but still
5. Just... The overall odd focus on Kuroji here, being the one who NiLU should keep a close eye on since they're the closest one to being a human.
6. Suzumi already has a baby in the form of Kurohebi, the oldest baby
So there. Please also read my analysis of NiLU in BotC to get the "full picture"
