Something to understand about Maine is that it is one of (or arguably the) whitest state in the country. Its racial demographics in 2020 are almost directly proportionate to its demographics in 1940. So any sort of immigrant, especially one from Japan, would stick out like a sore thumb and would be stigmatized on this basis alone.

Maine has always had very limited immigration, even less so before the lifting of the harshest (federal) restrictions in 1965. Despite this, there was a small but thriving Chinese community in Maine from around 1890 to at least 1920, with the first arriving in 1860-70. They worked mostly as laundrymen and were spread throughout the state, although centered in economic and population center Portland. Despite this, there are essentially no records of other Asian immigrants in Maine from before 1965. (p.g. 12) That is to say, there are no records about how Japanese specifically were treated during this time.

Race-based discrimination in Maine at the time was much better than it had been before 1930, when the Ku Klux Klan was a major political force. Unlike the standard image of the Klan - that is, a white supremacist group of all stripes rallying against increased black influence, the KKK in Maine was almost entirely a Baptist group focused on preventing immigration from Catholic nations, meaning Italy, Germany, Ireland, and Quebec (among others). While they were virulently anti-Catholic primarily, they were also generally anti-immigrant. Gerald Talbot, a Maine civil rights leader, reports that "fundamentally no different from the rest of America," when it came to discrimination in areas such as housing. While by 1944 the KKK had been extirpated as an organized political force, some vestiges of that line of thought would still be there in Maine's famously insular and nativist communities (nativist not in a racial sense, but in a cultural one; to this day, people "from away" are viewed with suspicion). Famously, Mainers often don't consider someone who has not lived in the state for at least three-six generations to be a true Mainer, instead being a flatlander. It is very tough for these communities, especially back then, to welcome anybody new, be they from New York or Nagasaki. Finally, as you know in 1944 there was a deep resentment of the Japanese and Japanese immigrants to this country as a result of the war in the Pacific, which was a national issue not confined to one state or region.

To conclude, while discrimination may not be as in-your-face as it would be as somewhere like Alabama, it would absolutely still exist and would in fact be exacerbated by the active war being waged by the Japanese. So while the Japanese man may be tolerated, he would not be considered a real member of the community for a long time and certainly not a true Mainer. I'm not sure how long your character has lived in Maine; if it is for a few decades already, they probably won't encounter much ire from the populace.

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