I have a little theory that a thing that makes Japanese website feel Japanese is their choice of typeface, which will almost always be something with robust CJK character support. This typeface is preserved when Chrome auto-translates the site.

But fonts with good CJK support have wider Latin letter-forms, even when not in `font-variant-east-asian: 'full-width'` mode. I write about this here: https://maxbo.me/subordinate-latin.html (and cite "the peculiar case of Japanese web design")