I want the OS to use English to display UI, but I need to read and write Japanese in applications and deal with files whose name is in Japanese.
When applications use Western fonts and display Japanese Kana and Kanji, the fonts do not look good. It seems to me that, by default, Ubuntu just assumes Chinese. Some Kanji look weird to me. For example, the "誤" in "誤解" or the "直" in "直接" do not look like the one used in Japan.
Is there any way to force Ubuntu to use a specific Japanese font when it is displaying Kana/Kanji in a Western font? Perhaps there is no way for the system to tell whether a specific text is Japanese or Chinese; but I do not read Chinese so I do not care if real Chinese texts are wrongly displayed in the Japanese font.
[Added in response to the comment]
Below is the output. I had tried to remove the Noto font series but they came back when I installed some applications. I also tried to remove fonts of languages I cannot read at all. Basically I just want Western European fonts (English, German, French, etc), Japanese fonts, and Korean fonts.
$ fc-match -s | head -15 DejaVuSans.ttf: "DejaVu Sans" "Book" DejaVuSans-Bold.ttf: "DejaVu Sans" "Bold" DejaVuSans-Oblique.ttf: "DejaVu Sans" "Oblique" DejaVuSans-BoldOblique.ttf: "DejaVu Sans" "Bold Oblique" n019003l.pfb: "Nimbus Sans L" "Regular" DroidSansFallbackFull.ttf: "Droid Sans Fallback" "Regular" NanumGothic.ttf: "NanumGothic" "Regular" FreeSans.ttf: "FreeSans" "Regular" FreeSansBold.ttf: "FreeSans" "Bold" FreeMono.ttf: "FreeMono" "Regular" FreeSerif.ttf: "FreeSerif" "Regular" opens___.ttf: "OpenSymbol" "Regular" DejaVuMathTeXGyre.ttf: "DejaVu Math TeX Gyre" "Regular" DejaVuSansMono.ttf: "DejaVu Sans Mono" "Book" DejaVuSerif.ttf: "DejaVu Serif" "Book" (the end)
I posted a question to a general Japanese Q&A site (which is not a technical web site). I asked if the "誤" and "直" in my first screenshot are used in Japan. I got two replies, and both of the Japanese persons said they were not used in Japan and they guessed those letters were simplified Chinese letters. But I think they are not simplified Chinese letters either, because I have seen that the left 言 part becomes a weird single line in simplified Chinese letters.