Question: I'm a Japanese major right now: Any suggestions on a second major that will open up more doors than my current major/minor?
Find and take one of the US Foreign Service Exam pre-tests. If you score reasonably well, start following the suggestions for working for the US State Dept who are hiring big-time right now and for the near future in asian languages. Damn, I wish the State Dept was hiring like that when I was in my early 20s (I scored above the 90 percental and still it wasn't good enough). In the same vein, Chinese or Arabic would be be a good 2nd major if you are really into language study.
If you're un-techie but into writing, language and Japan, maybe you might like taking coursework in "corporate communications", technical journalism, and the like. If you pass the official "Level 2 Japanese" test and have a tech. writing degree many Japanese companies will hire you (hell, if you pass Level 1 Japanese" and got a techical writing degree I'll hire ya).