I don't know about Japan specifically, but here are some general guidelines (many of which you may already be familiar with):
-If asked something along the lines of "tell me about yourself" (standard opening question in the US, don't know if it's the same in Japan), do not give an autobiography; also, know that there is a limit to how humble or boastful you can be: you won't stand out if you're too humble, but you'll look bad if you're too boastful (at the same time, if you don't boast about yourself, no one else will). Keep it concise and think of at least three points you want to convey about your character; only use three of them for this question, and keep the rest in reserve in case you need them later.
-If you have facial hair, remove it. It doesn't matter if it makes you look like you've got pox a couple days later (I speak from experience on this...), the interviewer doesn't know and no explanation, if they comment on it, will be taken well (but again, I don't know if this kind of commentary is usual in Japanese interviews). Cut your hair short (if male, women just have to make sure it doesn't look wild). It shouldn't be any wild colors, so if you look Asian (too lazy to dig and see if it's mentioned somewhere), dye your hair dark, no matter what it's natural color is. If you look foreign enough, any natural hair color should be fine.
-If you're a girl (again, lazy), your make-up matters (doesn't matter if you're a man or a woman, your looks are important; for women, this means that you're expected to wear make-up). It must be professional, so avoid anything flashy. If you suck at doing your make-up (maybe you have the same mind as me, in which such excessive self-beautification seems like a waste of time), get someone else to do it, even if you have to go to a shop before your interview.
-Make sure your clothes match properly and are in fashion; if you aren't sure what would be good, go to a specialty store for assistance. (Side note: do yourself a favor and buy all-seasons slacks if you don't have any already (and will be expected to wear slacks); Japan's summers are about the same as where I live, maybe worse from what I hear, but these slacks will keep you quite comfortable; had to dress up recently, and those slacks kept me from sweating through everything when I stepped outside, even though I was wearing a wool jacket at noon on one of the hottest weeks of the summer... The lengths people will go to look good...)
-Find someone (assuming no one on here knows) that knows the proper posture and body language to use; interviews are often swayed primarily by your appearance and your attitude, assuming you meet the qualifications for the position (they can even give you the edge despite a lack of qualification in the States, but I don't think that'll work in Japan). The delivery is just as important as the message.
-As Zgarbas said, practice your responses to the standard questions; however, make sure you can deliver them fluidly, and that any interruptions won't throw you off; I've actually found that the best way to stay flexible is to practice just enough so that you know what you want to say, maybe have a couple phrases in mind, then come up with the rest of it on site (then again, this might be hard to do with a second language...)
Again, I have no experience with Japanese interviews, but I tried to cover the things that are universal to making yourself look good (which is all an interview is, really). I'll be really interested to see what anyone with more experience thinks of these points in the context of Japan.
Edited: 2015-10-12, 9:40 pm
