Do you think Tanaka knows that Sebastian is something other than human, aka a demon? And if so, does that mean he is aware of Ciel's contract with him? In his regular (not shrunk) form, he is shown to be very intelligent and observant. Also sorry if this has already been answered in the manga, I'm still trying to fully catch up to the current chapters.
This hasn’t been answered in the manga, but I and others have blogged about it. I don’t think I’ve ever gone too deep into this topic before, so here ya go!
Personally, I don’t think Tanaka quite knows he’s a demon, no. But he must have some ideas… and a lot of questions.
Tanaka does realize that something is way off about real Ciel. In fact, in ch141, Tanaka is standing right next to real Ciel and Undertaker when this conversation occurs:
Sebastian: I am quite certain you lost your life that night. I would not be here otherwise.
Undertaker: Eureka! Right on the nose, you are… master butler!
Real Ciel: It’s true I died once that day.
Undertaker: What does it matter if he’s alive or dead?
Undertaker then explains that real Ciel’s “reanimated”.
And Tanaka might have overheard part of the previous conversation in ch130, before he had actually stepped out to the stairs and made his presence known to the readers. That goes:
Bard: H-hey. What the hell’s the deal with this guy, Sebastian!?
Real Ciel: Sebastian? I see. So you’re Sebastian. This is the first time we’ve actually met. How dare you do that to me that day.
Sebastian: I too… have never encountered someone like yourself.
So, Tanaka… being the smart guy he really is, regardless of how he’s being portrayed at any given time, has quite possibly gathered enough information to at least get the sense that Sebastian is someone (or something) not quite human.
If he heard the previous conversation, he knows that:
Real Ciel and Sebastian hadn’t actually met before, so real Ciel was already dead, or at least he was near death and no longer conscious. [We are to understand that Sebastian devoured his soul in order to cross over into the human realm, so real Ciel is officially dead by the time Sebastian takes any form before our earl and the cultists.]
However, Sebastian did something to real Ciel’s body. [Again, we know that he devoured real Ciel’s soul, but this could also be about removing the ring from real Ciel’s guts and then starting that fire.]
Sebastian has never encountered such an advanced reanimated corpse before. [Sebastian does go on to question Undertaker about the corpses on the Campania and at Weston, so Tanaka knows the walking and talking corpse he’s serving tea to is not quite like whatever Sebastian dealt with before, when he came back to the manor and was given a “day off”.]
From the conversation he definitely heard, he knows:
Real Ciel died and has been reanimated by Undertaker.
Sebastian would not be “here” if real Ciel had not died.
Tanaka’s main questions that might remain would be about what Sebastian did to real Ciel’s body (but more importantly his soul) the day real Ciel died… and what Sebastian actually means by saying he wouldn’t be here without real Ciel’s death. Would Tanaka realize this has more to do with real Ciel’s soul than his body? That’s the real question we have to ask to figure out whether Tanaka quite gets what’s going down.
Yana-san says in an old tweet that individuals are largely shaped by the people who raise them. Each person has their own dark or evil streak, but whether that becomes a strong part of their personality depends largely on influences by those closest to them in their formative years. She says our earl is greatly influenced by this demon, Sebastian. She also says Vincent loves his family (another tweet, I think) but has a very wide evil streak. Then she says that Vincent was mostly raised by Tanaka, hinting that Tanaka has a dark side we have hardly seen… yet.
Then we have all those demon cultists who are super excited (in ch135) to get their hands on Vincent’s children. The guy selling the kids doesn’t know who they are, otherwise he would have priced them much higher. The buyer recognizes them immediately and, without saying what he knows, says they are worth more than twice that. And then they are recognized by the guy who’s essentially just hosting them at his house before their… um… debut. I’ve written a few times before that the two main cultists (the two men at the sacrificial altar) are — I’m pretty damn sure — the same two guys standing in the background, in ch32, during Baron Kelvin’s memory of trying to talk to Vincent.
These two mysterious guys:
The weirdo who procures the kids for the sacrifice is the same guy who shows up at Kelvin’s manor just to tell him he managed to get those kids. Then grossly says he and the others will make up for Kelvin’s inability to attend. 🤢
Ok, so even if those aren’t the same two guys (but I think so!), Vincent was still being hovered around by people who participate in the occult, including ritualistic orgies and sacrifices to demons, trying to summon them. This is the first (and only) sacrifice to work for that cult, but that doesn’t seem to bother most of them, since (as Sebastian says) most demon cults are just about debauchery.
We don’t know how much of this Vincent ever knew about, let alone ever took part in (I hope not!!), but… I suspect he at least knew about some of it. It was his duty as Queen’s Watchdog to know about such things and keep the general public unawares of it. Not even necessarily to put the practices to an end. He probably allowed his fellow Evil Nobles to do as they pleased… as long as it didn’t become a problem for the crown. Or directly involve his own family. Like, he would never have offered up his own children to these creeps. But random waifs? I think he knew what the cultists were doing (generally) and just… turned a blind eye to it. 😔
You know how our earl stops Vanel and his thugs from selling drugs in England for the Italian mafia… but allows Lau to operate his opium den? Lau works as an informant for our earl, so they have a working relationship. It’s kind of like that, to me. When Vincent is watchdog, he allows some things to happen while stopping others. If it’s getting out of hand with polite society (like deaths amongst the peerage) or causing scandal for the queen, he breaks it up. But if it’s a fellow “evil noble” who acts as an informant or a colleague, and it’s only causing problems for the local riffraff on the streets, then “ok”.
I know that makes Vincent look bad, but… come on. He was the previous earl of Phantomhive and Queen’s Watchdog. He joked to his kids about being quite good with knives and saying hogtying is his specialty. He’s an Evil Noble.
All this tangential info about Vincent and the other Evil Nobles is to get to this: If Vincent knew what was going on with his fellow Evil Nobles, in general, so does Tanaka. Tanaka probably already knew that there were demon cultists amongst the visitors who came in and out of Phantomhive Manor.
But does Tanaka realize that’s how real Ciel died and Sebastian came “here”? If he doesn’t realize it yet, I think he might eventually figure it out. If not on his own, Sebastian might eventually reveal the truth.
If Tanaka does already know… that could be just about the only reason why he has stayed behind at Phantomhive Manor, serving the reanimated corpse of the rightful heir… unless he’s just biding his time to return to our earl’s side… with useful information about real Ciel and the other lords of the stars….