I've heard it said that one of the ways the history of the Norman conquest is written into the English language is in the way that the words for stock animals - pig/swine, cow, sheep - are Anglo-Saxon, as used by the peasants who had to look after them, while the words for the cooked meats as served to their masters - pork, beef, mutton - come from Norman French. It seems a bit too neat, but it illustrates what's basically a sound point: a language is a storehouse of the history of its speakers. French (and later Latin) vocabulary has been absorbed into English at a deep level, so that today often it's often possible to make a stylistic choice between Germanic and French/Latin alternatives for things and concepts, while new coinages can draw on either. There are fashions in these matters: a hundred years ago inventors were all about the Latinisms, or even Latin-Greek chimeras such as "television" (contrast German's homely Fernseher). In the computer age Anglo-Saxon has made a comeback, reflecting the more demotic and unbuttoned language of geeks on both sides of the Atlantic, but particularly in the United States.
English is full of "foreign" words, but when a new foreign word enters English it tends to go through period of quarantine known as italicization. It's not always clear how long this is meant to last. Is it still de rigueur to write de rigueur? May one write simply of the zeitgeist, or must it be Zeitgeist? Those two have been around for a long time, but no one thinks to italicize "karaoke", which is of far more recent date. Perhaps this is because with some terms the foreignness is the point, or they refer back to some particular point of origin: write Zeitgeist and you evoke Hegel; write "Spirit of the Age" and you evoke Hazlitt (or Hawkwind).
Japanese is much more thoroughgoing in its demarcation of foreign words, reserving a whole script (katakana) to their use. Katakana has a much longer history, and it's only in recent times that it's come to be associated with linguistic imports (I'm not sure why/how), but perhaps it's not inappropriate to see it as roughly equivalent to English italicization - especially since katakana (like italics, itself a much older script with its roots in Caroline minuscule) can also be used for emphasis with words of native origin. I suppose the wholesale import of Western (predominantly but not exclusively English) words is of fairly recent (post-Meiji) date, but it would interesting to know whether there will ever be a time when common words like "パン" (i.e. pan = bread - an import from
But, like English, Japanese also has another language in its deep history: Chinese. There are even two number systems, one native Japanese (hitotsu, futatsu, mittsu...) and one Chinese (ichi, ni, san...)* - and almost all the kanji have at least two readings, one Kun (Japanese) and one On (Chinese). So year (年), for example, is toshi in Japanese, but can also be read in the Chinese manner as nen. so that
What I'd be fascinated to know is whether Japanese writers ever make (or made) a choice between words of Japanese or Chinese origin for stylistic effect, and whether it makes a difference to the timbre of their writing similar to the choice between an English style in which French or Latin words predominate, and one that maximizes words with Germanic roots.
* There's no French number system quite like that in English, although we do have count words like "dozen", which obviously derives from douze.