In Dr. Stone, the characters make Katanas. The term they use is translated as "Japanese katanas" in the version I'm watching, but the original term they use is 日本刀. In the show they use forging techniques that, barring historical rigor that's not the strength of the show, are presented as historically accurate for making katanas.
Why were they referred to as 日本刀 in the original dub and not 刀? Is this a case of semantic narrowing in loanwords where English loaned 刀 to mean 日本刀 but in Japanese it's a more generic term, like they did with アニメ (animation) vs "anime" (Japanese animation)? How do these words work in Japanese and which one am I to use in which context?
by Matalya2