I was gifted a 20 year old car in october that I have permission to sell once school's out and if I get accepted that should bring in at least $3,000-$5,000, so I'm sort of betting all my chips on that working out since I'm not currently employed.
As for exchanging money, I was told by BoA a couple years back that trying to change money to yen at the bank was a pretty bad idea. One, on top of the rates, there's fees because they have to actually order the money from japan because of course they don't keep tons of foreign money hanging around, so you'd have to pay for that to be shipped and any fees associated with that (tariffs for example), etc. They told me that it would be better to change money at the last airport I'd be in before embarking to Japan. I found this to be a pretty good strategy, personally. Bring maybe $375 with you to the airport to exchange at the booth (I try to aim for ¥30,000 in my pocket, so between the dollar being in the hole right now and the obligatory booth fee that you cannot avoid, I try to greatly overestimate), then after that you can pull out funds with your foreign debit card from 711 with no fees or small fees (depending on your bank). 711, if memory serves, does not charge any fees for foreign card withdrawals. I was even able to talk BoA into waiving all bank fees for international transactions back then, but I'm not sure they do this anymore. None the less, it is ALWAYS worth calling up your bank and telling them what you're doing and asking them if they can hook you up some how and maybe take mercy and waive international transaction fees (especially if your bank does not have a partner japanese bank). You will have to call your bank anyway to let them know that you will be abroad for a year or two so that your card is not temporarily suspended for unusual use.
So, take full advantage of the call and see if they can cut you a break while you give them the dates you believe you'll be gone for.
There's also an extremely competitive currency exchange booth right outside of akihabara station in Tokyo that you could try to pay a quick visit to during orientation that always gives you a little more bang for your buck even if the current rate is a little less advantageous for your currency.
So, for those worrying about it, that's been my personal experience and it's worked out quite well.
Save up your money, keep it in your home country's bank account, take out around $375 USD to exchange at your last port of call before you leave your country so that you have cash on hand and don't have to think about it for your first two days or so so that you can adjust, and then just pull from your home country's account as needed from a 711 ATM once in Japan.
There are probably other strategies for going about this, haha. I just thought I'd share what's worked for me.