Bill Poser in Language Log responds to Norimitsu Onishi's statement from A recent Letter from Asia:

Of all languages in the world, Japanese is the only one that has an entirely different set of written characters to express foreign words and names. Just seeing these characters automatically tells the Japanese that they are dealing with something or someone non-Japanese.

with some explanations about the Japanese written system, which consists of three character sets: kanji "Chinese characters", hiragana and katakana. Skipping the details,

hiragana is the default, while katakana is marked. When you want to mark something as special, you use katakana, rather like italics and scare quotes are used in English <...> but it isn't really very different from the English practice of writing words and expressions still perceived as foreign in italics, such as ad hoc and force majeure.

There is an ongoing translation of Joel Spolsky's opuses into various languages, performed by groups of anarchist-volunteers. I participated for a while in this teamwork, and our team didn't have an official language to discuss translations, so there was a mixture. Some were more comfortable with Russian, some with English, and most switched from one to another somewhere in the middle of the sentence. Later, I exchanged few E-mails with a member who used exclusively English. Following his manner, I soon found that it became easier to talk about translations, because Russian words stood out, and there were no need to use quotes or other means to mark which part of a sentence is what the sentence is talking about. Hofstadter's famous quine

"is a sentence fragment" is a sentence fragment

could acquire an alternative, "quotes-free" incarnation. Japanese would provide yet another incarnation, with its build-in katakana feature.