That's why I used quotes for "realism." If you require historical accuracy then, no, it will not meet your REQ. Thus the comments I made about it.
"Sci Fi" and "Parallel Universe" are convenient close fits, for lack of more perfect keywords.
It is a fairly immaculate telling of a story that could
have happened in the middle of the last century if our world had followed a slightly different path going into and coming out of WWI. "Parallel Universe" is a bit too strong; "Alternate Timeline" or "Alternate History" would be a bit more precise. The events depicted are very significantly based upon the real history of the Russian vs. U.S. space race ... had it occurred in Asia a decade or so earlier.
- thus, I stand corrected. Thank you! In my memory, I was sure it was Earth; clearly not. I need about six months with nothing to do but watch anime. So many new titles on my pile, and I want to re-watch about a hundred+ I've loved over the years ...