Captain Marvel Jr is turning Japanese (I really think so)
Whoa. This is the sort of Golden Age stuff that gives you a jolt of realization how different the wartime attitudes were. At least the Americans given the Yellow Curse didn't suddenly sprout fangs or need thick-lensed eyeglasses. This is from CAPTAIN MARVEL JR# 10 (August 1943) written by Otto Binder with art by Mac Raboy. (By the way, I don't believe "Kursyu"is an authentic Japanese name but then our hero's name is "Freeman," so there may be some symbolism involved.)
The Marvel Family stories were wildly inconsistent in some ways. Nearly all the time, whatever had happened to the kids did not show up when they changed to the Marvels, but there were exceptions. Usually, Junior would be unaffected by any weird serum that Freddy had been given but not here. Although he doesn't start spouting "Banzai!" and referring to the Mikado (which is odd in itself). The idea that an injected serum could instantly change your skin color (here the brightest yellow available, created an inner eyelid fold* and give you intense loyalty to the government of another country (while still speaking English) makes no sense. But then, this was an era where in the movies John Carradine could give an injection that transformed a woman into a gorilla or where Boris Karloff could casually perform brain surgery alone in his office after hours. I don't know if people had a more willing suspension of disbelief or were just less well informed back then. Maybe both.
_______________________
*To be honest, if you had never seen an Asian person close up (and millions of Americans of that era hadn't), and you had never learned about eyelid folds, you might well accept the common phrase about "slanted eyes" and think, yeah that makes sense. From all reports, most Asians had similar misconceptions about Europeans. Information just wasn't instantly available on your phone back then.