Thanks for all the advice. To address the most common things people have brought up:
1. I'm a gringo from Nevada. I'm 40 years old. I lived in Korea for 15 years, and just moved to Japan to get this tenure-track professorship. My Korean is pretty good, my Japanese is very beginner level. This is honestly a big part of the imposter syndrome you guys correctly point out. In Korea, I was able to do anything a native could - argue about the fine print in an insurance contract, talk trash to friends, parody celebrities on TV, etc. In Japan I'm just now getting to the barest survival level. It feels super weird to suddenly have a much higher position when I can't tell my neighbor "hey, I like your garden" without the help of Google. Going back to Korea once a month or so on weekends just so I can feel competent has honestly been a godsend for my confidence and mental health.
2. The advice to be myself is appreciated and true, but I tend to think of "who I am" as a function of "what I do." And it's also complicated by the fact that "what I did" well enough to get this job, and to get most of my opportunities in Korea, was handle dangerous and/or difficult people in such a way they didn't cause a mess. Representative example, I have been an editor for the team creating the national teacher's exam in Korea three times now. This process is very high security (people quite literally fly spy drones over the facility trying to steal exam questions) and very high stress. You basically get locked in a conference room with 9 other people, working between 12 and 20 hours a day, and you can't leave for three weeks. If the other 9 people are cool, it's simply hard. If the other 9 people are psychotic ego-maniacs, you end up with 50% of the team suffering from mental breakdowns and/or stress induced illnesses. The first two times I did it, my team was cool. The last time I did it, we had four certifiable raging sociopaths trying to mentally break everyone else so they could dominate the test making process. All three times I got high commendations from prestigious people because I was able to both function in these environments and to keep the psychos at least somewhat under control. The third time around, with the psychos, my honest feelings were that I wanted to murder about half the people in the room. The people I wanted to murder, on the other hand, were some of the same people who recommended me for commendations. All of them think I'm their "hard to read and slightly scary friend."
The person who recommended me to the Japanese university and is by far most responsible for me getting this job is a kind hearted and well intentioned woman with absolutely disastrous social skills. She recommended me partly because I've spent 10 years smoothing over the ruffled feathers that literally always trail in her wake and partly because I've spent those same 10 years making good first impressions on her behalf. I strongly suspect I got recommended for this job in particular because she wants to make a closer relationship with the president of my new university and sees me as a bridge. Before I even got to Korea, one of my jobs was making friends with the local gangsters and convincing them to stop shooting up to local 7-11, etc. Understanding and dealing with social cues is and has been a pretty central part of my skillset almost my entire life.
I did well with teaching my classes (which is honestly also about 70% managing egos anyway), and I've published books/papers/textbooks, but there are certainly people who have published more and got passed over.
3. There are core parts of my identity that I'm not going to compromise. My core professional goal is to publish, support, and maximize the impact of a thing I call the "overcoming justice project." I won't get into the details here, but I'm trying to do a Guns, Germs and Steel of ethics. I strongly feel that the stuff we call justice (regardless of its political orientation) is highly problematic for people in general and disastrous for young people. I badly, badly want to offer an alternative, and I think I've created the first steps on the path to operationalizing this alternative. There's no fight I wouldn't undertake to move this project forward.
I also consider it a duty to strengthen and ennoble "my people," by which I mean anyone under my protection. Close friends, valued family members, my fiance, the people who work under me - this is not open to negotiation and I will not compromise.
Then there are the things that are less core. I like racing and weightlifting. I enjoy Michael Mann films and engineering projects. I like to read philosophy and history. I really enjoy writing fiction. I don't want to compromise on these things, but I would compromise them to protect the core stuff.
Finally, there's the stuff I barely care about. Fashionable clothes. Beer. BMWs. Luxury anything. Golf. I'm willing to twist this stuff around in any which way serves my absolutely core values or my less core values. The question you guys have helped me to answer - excellent suggestion on the used suits btw - is how to twist this stuff around effectively.
4. Betrayals and the prevention thereof. This absolutely puts up walls between myself and others. I need to learn how to better balance snake pit survival strategies and toning it down for safe times/places. I'm not good at this balance.
My previous job was a snake pit where everyone was trying to stab everyone in the back. The job before that was a snake pit. Even as a kid, I quickly learned that any time you show a weakness, it will be used against you. I have a procedure to manage these things.
a) Whenever I walk into a new environment or meet new people, I pay very close attention to who defers to who, and why. Understanding the social hierarchy is key to determining who is going to go after who, and when.
b) I analyze the people around me to find their weaknesses. This helps in two big ways. First, if the person turns out to be treacherous, I know how to apply pressure. Second, if the person doesn't turn out to be treacherous, I can protect or shield their weakness in a way that makes it clear that I could hurt them if I wanted to (healthy fear), but also that I choose not to hurt them (healthy trust).
c) I encourage people to lie to me. People lie to cover up insecurities, protect weaknesses, or distract from their schemes. If I can catch a person lying, I know exactly what they want to protect and hide.
This system is not working so well at the new job for a couple of reasons.
a) I can't find the snakes. Most likely this is because snake pits happen when the leadership is weak, and the leadership at this new university is quite strong and dynamic. However, my gut feels like I can't find the snakes because I'm not looking hard enough. This is probably not rational and I probably need to chill, which I'm not so good at doing.
b) Finding weaknesses is mostly quite easy, but using them is not. This is the first time in my life I've found significant numbers of people who genuinely cover for each other. They don't even bother hiding their often quite obvious weaknesses because they're confident that grandma/cousin/father will cover for them. I can't stress how different this is that what I'm used to. Weaknesses in my experience have always been blood in the water.
c) Some of these people are the management equivalents of Picasso or Mozart. I'm thinking specifically of a man in leadership here. I can feel him playing the social dynamics and power games and I recognize many of the tricks he plays. He's really berkeleying good at them. Masterful. Better than me. There's a confidence and ease this guy displays I'm in awe of, a casual but incredibly effective way he not just commands but earns obedience and loyalty from very high status people. I consider this all very good, and I'm going to study the guy and learn from his techniques. But it puts me in the position I usually try to put others. This guy could hurt me, and I'm pretty sure he's figured out my weaknesses, and I need to trust that he won't use those weaknesses against me. So far so good, and he's doing amazing things to help my career and support my ambitions, but he's still better at the game that I am, and I'm playing on his terms.
Also, while I'm pretty sure I recognize the tricks he uses to win the social dynamics game, I'm positive he's figured out my tricks. I've invited him to lie to me several times and he knows what I'm doing. There is no insecurity I've found, and the stuff that looks like weakness - he has a family member with physical and mental difficulties, he's a member of a not-very-popular ethnic minority - is simply not.
5. Spending on status displays. You guys made some very good points about spending to keep up with the Joneses. I'm not going to buy a BMW (or any new car), and I'm not going to spend big money on shoes or suits. That said, I just did the paperwork to pick up an NB Miata that will be delivered next week. It's a really neat little car with Tein adjustable coilovers, some really sweet forged Racing Hart rims, a fart cannon, and a sparkly dildo gear shift. I am not going to hide it in shame, but I probably should replace the dildo and fart cannon.
Thanks for all the comments. Very helpful.