I know maybe 3 dozen words in Japanese and the best I can do is “Nandemonaiya” which is something like “never mind” but could also maybe be used to say “forget about it”. Japanese is a super polite language though, so “it doesn’t matter” may be about as good as it gets? Also, Japanese tends to throw nouns out to mean a thing is like that noun, like you might call a homebody an “otaku” (house, as in they never leave it) (commonly used to refer to anime fans, as in they stay in all day watching anime) so maybe the word for “shit” or “garbage.” Shit, as in just saying the curse (like “dammit”) would be kuso (usually the vowels are silent, so it just sounds like “hiss” but with a K (but not “Kiss” if that makes any sense). But “kuso” is more like “dammit,” like I said, I wouldn’t use it to say I don’t care, more that I’m annoyed and bothered.
知らない (shiranai) can be a pretty biting way to say you don’t care about something/someone’s situation, but it’s not vulgar. しらねぇ (shiranee) would be a more vulgar way to say the same thing, that’s probably closer. I don’t know if there’s a metaphorical idiomatic phrase like the other languages in the OP.
Anyone who knows Japanese wanna weigh in?
I know maybe 3 dozen words in Japanese and the best I can do is “Nandemonaiya” which is something like “never mind” but could also maybe be used to say “forget about it”. Japanese is a super polite language though, so “it doesn’t matter” may be about as good as it gets? Also, Japanese tends to throw nouns out to mean a thing is like that noun, like you might call a homebody an “otaku” (house, as in they never leave it) (commonly used to refer to anime fans, as in they stay in all day watching anime) so maybe the word for “shit” or “garbage.” Shit, as in just saying the curse (like “dammit”) would be kuso (usually the vowels are silent, so it just sounds like “hiss” but with a K (but not “Kiss” if that makes any sense). But “kuso” is more like “dammit,” like I said, I wouldn’t use it to say I don’t care, more that I’m annoyed and bothered.
知らない (shiranai) can be a pretty biting way to say you don’t care about something/someone’s situation, but it’s not vulgar. しらねぇ (shiranee) would be a more vulgar way to say the same thing, that’s probably closer. I don’t know if there’s a metaphorical idiomatic phrase like the other languages in the OP.
For vulgarity in Japanese in general, you should watch this: https://youtu.be/GcjbwkBQeO8