It might have been the recent PR about Ridley Scott's movie adaptation of The Martian, but I've seen the Japanese translation (by Onoda Kazuko 小野田和子) prominently displayed in a couple of bookstores recently. The translation of the title is interesting: Kasei no hito 火星の人, literally "Person of Mars."

Is there no word for "Martian" in Japanese? No, there is one: Kaseijin 火星人. The Kasei part means "Mars" (lit. "fire planet") and -jin, meaning "person," is the suffix used to form words such as Amerikajin, Nihonjin, Chikyūjin ("Earthling"), etc. You'll notice that -jin is written with the same Chinese character as hito in Kasei no hito; -jin is the Sino-Japanese pronunciation, while hito is native to Japan.

So it would have been possible to translate the title literally. Why wasn't this done? I poked around looking for opinions online, but there weren't many. A couple of people argued that Kaseijin implies, you know, a tentacley or at least green alien, so it wouldn't be appropriate for a story about a human stranded on Mars — but this is the case in English, too; that irony is the whole point of the title. This blog entry, interestingly, links the Japanese title to lightness and readability, which may well have been a consideration. (It's worth noting that Kasei no hito doesn't have any explicit meaning, either; it doesn't have the strong creature feature associations of "Martian," but neither does it necessarily imply that the "Person of Mars" is human.)

I wonder, actually, if the different titles might not reflect slightly different understandings of what it means to be an X-jin. Just as being stranded in Japan didn't make William Adams Japanese, so being stranded on Mars doesn't make Mark Watney a Martian, not even to the extent where the joke makes sense. Insisting on a connection between ethnicity and nationality isn't unique to or universal within Japan, of course, but I think it's fair to say that it's more common here than it is in California, where Martian author Andy Weir was raised.

(In a way, I guess this hypothesis is the same as the argument that Kaseijin implies a bug-eyed monster, really, just with the implicit connections to ideas of nationhood made more explicit.)