About the identity of the Nogitsune...
So this Nogitsune chooses to present itself to Stiles in a specific form, probably as one of its past (or its latest) host. Before we can actually see what this Nogitsune looks like, we know that he can speak Japanese. Since the Nogitsune myth comes from Japanese folklore, we can’t really tell if the ability to speak Japanese comes from the spirit itself or the host (and by host I don’t mean Stiles, but this creepy guy up there with the bandages on his face).
Eichen House is the facility from which Barrow escaped (or was set loose), but it’s also where Stiles turns out to be in his hallucination when he’s talking with the Nogitsune. The easiest way to link this facility to the Nogitsune is by looking up the meaning of eichen; in German, it means calibrate (which would indeed be an appropriate name for a mental institute), but it also means oak. Now this is not the only mention of the word “oak” in 318. When Mr. Yukimura translates the voicemail Allison got on her phone, he mentions an internment camp called Oak Creek, which he then assures never existed. Oak Creek might have easily been a code name for an “underground” internment camp during WWII: Eichen House.
Now as the Nogitsune reveals himself to Stiles, we get a closer look at what he’s wearing. It looks like an army uniform, which is confirmed by the patch we can very briefly see on his shoulder. It’s a US Air Force patch from WWII. So does that mean that the Nogitsune was a Japanese-American aviator during WWII? It sure looks like it.
When Lydia leads everybody to Eichen House and they realize the basement is empty, we can see the Kanji for self (己)carved into the wall, where the Nogitsune drew it with chalk in Stiles’ hallucination. Could it be possible that the Nogitsune carved it himself half a century ago, when he was himself a prisoner in this unofficial internment camp? Now I don’t know about you but I feel like carving something like this into a stone wall must have been a pretty violent act, urged by a desperate need to have something to hold on to, a need to remain oneself and keep one’s sanity. Was the basement a torture room? Is that why the Nogitsune’s face and hands are covered in bandages? Because he was tortured into madness?
Now let’s go back in time a little bit. At the beginning of 3B, when Stiles still couldn’t read, a few elements foreshadowed his possession by a Japanese spirit. These symbols on his locker combination for example. Now I know these aren’t Japanese symbols but they could still translate the Nogitsune’s inability to interpret romaji and Arabic numerals. It would still be weird if a Japanese-American soldier from WWII couldn’t read English though, right? But for an ancestral Japanese spirit, it doesn’t sound so absurd.
When Stiles freaks out in 314 when he has to read in front of the History class, the letters on the page start falling down. I wondered why that was, but then I remembered that sometimes Japanese was written vertically (which even though it’s still used today in newspapers and stuff, it’s the traditional way to write it). When we take a closer look at that page, we see that it’s about Japanese internment camps. Could that be the reason that Stiles (or rather, the Nogitsune) freaks out all of a sudden? Because it brings back horrible memories from his own camp experience?
I think we all thought at that moment that Stiles was having another panic attack, because he couldn’t read and he was sick of this BS. But when Scott asks "Is this a panic attack?", Stiles gives him a subtle nod as if to say “no” (look at the gif, it feels like Stiles is even mouthing no). Stiles must be an expert on panic attacks, right? If this isn’t him freaking out, could it be what’s possessing him?
Now I’m not really sure what are the exact terms of Stiles’ possession by the Nogitsune. But with everything that I just observed, and Stiles’ own words in 313 when he experiences his first hallucination ("it was like a dream within a dream"), I’m wondering if Stiles could be under a double possession (which would explain the we that the Nogitsune keeps using: “we’re trying to save your life”). The actual trickster spirit on the one hand, and this aviator guy on the other. I feel like the Nogitsune spirit looks for hosts with mental weaknesses (the soldier’s madness because of his internment, and Stiles’ brain atrophy) either because they are easier preys to mess around with, or maybe, on the contrary, in order to help them find themselves (己) again. We know that we’re going to learn Stiles’ real name this season, and there have been theories going around that this would be what rids him of his possession. In other words, someone calling him by his real name (Lydia? Holland said she’d be “inducted into the Stilinski family” in the recent spoilers) might help him regain his sense of self.