Are Vampires Youkai and Tsukumogami? I ask since it makes me wonder if wonder if hearsay/stories/etc may have influenced Slayer in some way if he is a Youkai. Sorry if I'm misunderstanding.
This is a difficult question to answer because really it depends upon the origins of the Tsukumogami in question.
Most Youkai are influenced by stories/folklore surrounding their origins, or if they aren’t influenced by those, they are influenced by the human attachments to objects that are connected to their origins.
Slayer has not stated openly if he is connected to any such folklore... though he is deeply involved with conflicts related to Humanity’s past history involving Vampires.
Slayer is not by any means the OLDEST vampire in existence, or even the most powerful (or at least he makes no indication that that is the case).
As I said, there are different kinds of Vampires...
Even something like Flament Nagel... an axe influenced by Alchemy and Blood Rituals... is something “similar” to a Vampire in nature. But unlike a normal Vampire, he does not have supernatural abilities and is bound (more or less) to his axe weapon-form and does not have a humanoid body.
Even something like Testament is “kin” to Vampires in some capacity, even though he is still technically a Gear.
Does being a Vampire mean they are Youkai? Not necessarily.
The term “youkai” iself can mean many things:
妖 “bewitching, calamity”
怪 “mystery, apparition”
Wordplay is often tied to folklore, so you could say that any “ghost” born of a calamity or tragedy is a Youkai in and of itself!
Vampires by themselves are still something of a biological mystery... at least as far as human understanding of them goes.
To gain ludicrous amounts of power just from absorbing blood is almost unheard of, scientifically speaking.
Well, even so, much of what we know about Vampires... vague though that knowledge often is... is folklore just as you would expect of any Youkai.
But, in the realm of Guilty Gear, where the Backyard can establish Human Imagination as Reality... that sort of power is more legitimate than first glance would otherwise dictate.
The larger question would be: “where do Vampires end, and Youkai begin?”
Because of how supernaturally powerful Vampires are... they far exceed traditional notions of Youkai by leaps and bounds... so in that essential aspect, Vampires are a step beyond what Youkai basically exist as.
Are Vampires an evolution from Human Knowledge and Consciousness? Again, that idea is very unclear. Even Slayer has no immediate definition for what he himself is... and so he simply referred to himself as an “Ishu” (Outsider/Exception).
Vampires are by no means the “exceptions” to the rules of the many forms of life in this world, but they are just one of many possible beings.
Youkai, you might say, are just “other possibilities” that Vampires and other beings might take.
