You should move to Europe over America IMO for sure. USA is not a good place.
I do not like Japanese culture and aesthetics, would go there as a tourist if I could tho, but not live. And I am not sure it is a good place to live, people are quite racist and very strict at work, big workaholics. I am not sure how much this is true, but it's worth investigating IMO. And it is hard to get citizenship there.
You will probably prefer western Europe, esp if you go for educational purposes. I wouldn't leave Eastern Europe, unless for a partner or some really amazing job, MAYBE nukes, maybe, how bad can a wasteland be? Mainly because eastern culture is so much better IMO, people are normal here, or insane but in a normal way.
Europe is certainly a better choice for Peach.
She isn't one to spend a lot of time learning something like a new language, so she will be walking into either situation with just English. I feel like the transition to European life would be both culturally and linguistically easier. Regardless we have actually been planning on a tour of eastern Europe since 2018 given that was something i was going to do around the time we met.
The rest is not addressing you in particular Good.
Japan has a rich intellectual history as well and our a math and physics power house. Just want to share given this stuff is often overlooked when talking about Japan and its culture.
Japanese mathematics
Japanese Mathematics in the Edo Period
Seki Takakazu
Seki Takakazu (関 孝和, c. March 1642 – December 5, 1708),[1] also known as Seki Kōwa (関 孝和),[2] was a Japanese mathematician and author of the Edo period.[3]
Seki laid foundations for the subsequent development of Japanese mathematics, known as wasan.[2] He has been described as "Japan's Newton".[4]
He created a new algebraic notation system and, motivated by astronomical computations, did work on infinitesimal calculus and Diophantine equations. Although he was a contemporary of German polymath mathematician and philosopher Gottfried Leibniz and British polymath physicist and mathematician Isaac Newton, Seki's work was independent. His successors later developed a school dominant in Japanese mathematics until the end of the Edo period.
While it is not clear how much of the achievements of wasan are Seki's, since many of them appear only in writings of his pupils, some of the results parallel or anticipate those discovered in Europe.[5] For example, he is credited with the discovery of Bernoulli numbers.[6] The resultant and determinant (the first in 1683, the complete version no later than 1710) are attributed to him.
Shigefumi Mori
Shigefumi Mori (森 重文, Mori Shigefumi, born February 23, 1951) is a Japanese mathematician, known for his work in algebraic geometry, particularly in relation to the classification of three-folds.
He generalized the classical approach to the classification of algebraic surfaces to the classification of algebraic three-folds. The classical approach used the concept of minimal models of algebraic surfaces. He found that the concept of minimal models can be applied to three-folds as well if we allow some singularities on them. The extension of Mori's results to dimensions higher than three is called the minimal model program and is an active area of research in algebraic geometry.
Kiyosi Ito (A lot of financial mathematics are built around his work)
Kiyosi Itô (伊藤 清, Itō Kiyoshi, Japanese pronunciation: [itoː kiꜜjoɕi], September 7, 1915 – 10 November 2008) was a Japanese mathematician who made fundamental contributions to probability theory, in particular, the theory of stochastic processes. He invented the concept of stochastic integral and stochastic differential equation, and is known as the founder of so-called Itô calculus.
Kenkichi Iwasawa
Kenkichi Iwasawa (岩澤 健吉 Iwasawa Kenkichi, September 11, 1917 – October 26, 1998) was a Japanese mathematician who is known for his influence on algebraic number theory.
Iwasawa is known for introducing what is now called Iwasawa theory, which developed from researches on cyclotomic fields from the later 1950s. Before that he worked on Lie groups and Lie algebras, introducing the general Iwasawa decomposition.
Mikio Sato
Mikio Sato (佐藤 幹夫, Satō Mikio, born April 18, 1928) is a Japanese mathematician known for founding the fields of algebraic analysis, hyperfunctions, and holonomic quantum fields. He is a professor at the Research Institute for Mathematical Sciences in Kyoto.
Yutaka Taniyama (谷山 豊, Taniyama Yutaka[1], 12 November 1927 – 17 November 1958) was a Japanese mathematician known for the Taniyama–Shimura conjecture.
Taniyama was best known for conjecturing, in modern language, automorphic properties of L-functions of elliptic curves over any number field. A partial and refined case of this conjecture for elliptic curves over rationals is called the Taniyama–Shimura conjecture or the modularity theorem whose statement he subsequently refined in collaboration with Goro Shimura. The names Taniyama, Shimura and Weil have all been attached to this conjecture, but the idea is essentially due to Taniyama.
Goro Shimura
Gorō Shimura (志村 五郎, Shimura Gorō, 23 February 1930 – 3 May 2019) was a Japanese mathematician and Michael Henry Strater Professor Emeritus of Mathematics at Princeton University who worked in number theory, automorphic forms, and arithmetic geometry.[1] He was known for developing the theory of complex multiplication of abelian varieties and Shimura varieties, as well as posing the Taniyama–Shimura conjecture which ultimately led to the proof of Fermat's Last Theorem.
Shinichi Mochizuki
Shinichi Mochizuki (望月 新一, Mochizuki Shin'ichi, born March 29, 1969) is a Japanese mathematician working in number theory and arithmetic geometry. He is one of the main contributors to anabelian geometry. His contributions include his solution of the Grothendieck conjecture in anabelian geometry about hyperbolic curves over number fields. Mochizuki has also worked in Hodge–Arakelov theory and p-adic Teichmüller theory. Mochizuki developed inter-universal Teichmüller theory,[2][3][4][5] which has attracted attention from non-mathematicians due to claims it provides a resolution of the abc conjecture.[6]
I ended posting only mathematics stuff, but I could easily do the same with Physics and it would only be more impressive.