2 of her 3 trademark firearm patterns are currently standard issue for the US armed forces. I wouldn't call that "notably non-American", unless you mean country of origin, in which case she's Belgium-Israeli-Italian.
It's not unlikely to think she could hit up one of the several US military bases in Japan. They'd at least be ostensibly be better equipped and easier to find than the local Yakuza hideout.
langrisser said: The problem is that the fighters aren't American.
Remember that the series is in the not too distant future, meaning technology will be somewhat different in their universe.
soluuloi said: She's inside a witch's maze, nuff said.
Sybil Ludington was a patriot (and MG, natch) who led a 40-mile midnight ride to warn a Connecticut town about the approaching British troops, twice the distance of Paul Revere's. Hers was solo (unlike Paul Revere, who was actually accompanied by several other men) and unlike Revere, she was not caught. (Not STOPPING AT A TAVERN TO GET DRUNK, unlike Revere and company, probably helped.) Unfortunately her gender made her accomplishment much less well known. Paul Revere became known to every American schoolchild (in part due to his name rhyming with "hear" in Longfellow's poem), while poor Cybil Ludington fell into despair and became a Witch. (That said, can YOU think of anything that rhymes with "Ludington"?)