Yep, no sims. I looked for quite a while and couldn't find any. You might be able to simply enable international calling but I recommend just calling Sprint and adding the international calling plan. Like I said, you can add it only for the time you'll be there and they'll prorate the price for you (I paid something like $2 for the time I was there).
And yeah, keep your calls short. $1.69/min adds up in a hurry. I was there for a week and racked up a $300 bill just for my Japan calls. Good thing it was covered by work.
