Pictured: Poster for the first Japanese–Philippine propaganda film Dawn of Freedom (Ano hata o ute korehidōru no saigo). Although presumably about a friendship, some analysts (e.g. Jennifer Robertson & Markus Nones) noted that certain scenes came across as suspiciously homoromantic.

There is so little talk about homosexuality in early Shōwa Japan that this may well be the first time that you have encountered any. I’ve had trouble finding books and articles on this subject (not even Wikipedia has much to say about it), and the few works that I did find discussed it within a more general context. I thought that the number of works on the LGBT+ community in Fascist Italy was awfully small until I looked into Imperial Japan!

Nevertheless, I likely have enough information to provide you with an overview. The good news is that was no conscious, direct effort to oppress gay folks within the Japanese Empire, partly due to the category of homosexuality being unknown at that time. Quoting from Mark McLelland’s Queer Japan from the Pacific War to the Internet Age, page 47:

The […] Japanese attitude [was] that homoeroticism is a widespread response to be expected in homosocial environments and not a pathology particular to specific individuals. Indeed, Pflugfelder suggests that Japan’s “relatively benign” stance toward male–male sexuality during wartime was a result of “the greater compatibility of male–male erotic behavior with hegemonic masculinity within the prevailing gender system”.

Unlike policies enacted by Japan’s ally Nazi Germany, there was no organized campaign to eradicate homosexuality from society; unlike the situation in the United States, there were no campaigns directed at removing “sexual deviants” from the armed forces. In fact, male–male sexual interaction remained unregulated by law throughout Japan’s years of militarism; postwar accounts of homosexual relations during wartime suggest that certain modes of homosexual interaction were tolerated within the military, particularly between senior and junior men.

The bad news is that heteronormativity only intensified after the invasion of Manchuria, making long‐term same‐sex relationships difficult—if conceivable at all. Pages 37–8:

Throughout the 1930s and early 1940s, the government’s pronatalist policies and its support for registered prostitution resulted in sexuality becoming increasingly heteronormative for both men and women. Lower‐class women were recruited to staff Japan’s many brothels, while women from “good families” were allowed no sexual activity outside of marriage.

Men too were caught up in debates about the proper deployment of sexuality. Family planning and advertisements for contraceptive devices were banned, but the authorities tolerated advertisements for medicines purporting to increase male potency or cure such common ailments as nocturnal emissions and premature ejaculation.

These advertisements often featured female faces or other body parts, reinforcing the assumption that “men’s sexual desire was to be shared with women”, particularly wives, whom husbands were encouraged to dutifully impregnate. Condom advertisements were also permitted, although it was their “hygienic” potential that was stressed, not their contraceptive function, suggesting that they were intended for extramarital activities.

In the homosocial environment of the armed forces especially, Japanese men were encouraged to express themselves heterosexually through government‐sponsored military brothels, euphemistically known as “comfort stations” (ianjo), in which women from Japan’s colonies were forced to serve as prostitutes.

\ Thus, while it may be surprising that the Imperialists could fool around with other blokes, it was expected to be a short phase, a brief detour before returning to heterosexual life, and was not to be taken seriously. It was not to be discussed (in public) either.

It would be useful to have input from elderly Japanese discussing how heteronormativity impacted them, but unfortunately I have no examples.