Thank you for the information. But I would advice that people linking to local Japanese fonts first check how those fonts look on your webpage. YuGothic in particular looks quite bad to my eyes, whereas Meiryo looks good most of the time. Also note that Hiragino is a Mac-only font, while YuGothic and Meiryo are Windows-only fonts.
I had not heard of Montserrat until you mentioned it. It seems to contain Japanese Katakana, Hiragana and Kanji. Each font is about 200k. So if you want Black and Bold and Thin on a single web page, most people won’t have that font on their computer and when used as a Web Font it would mean 3 downloads totally 600k.
Of course, when mentioning Montserrat in “font-family” it assumes the font exists on the computer and if it doesn’t other fonts listed within “font-family” are used as a fall-back. What this means is, since most people won’t have Montserrat on their computer, Montserrat probably won’t be used when displaying your website to 90% of the visitors. What will be displayed is the fall-back font instead.