It's (probably) a boy!
So by this time most readers of this blog (all 3 or 4 of you) have probably heard that we have a tentative gender identification.
We went for the 6 month checkup on Sunday and Dr. Fujioka told us that "the probability is very high" that the baby is a boy, but it's still not 100%. We saw the ultrasound and Dr. Fujioka pointed out what may or may not have been the elusive baby balls, but she said because the baby is facing away it's very difficult to tell. Hopefully we'll get a clearer picture on the 7 month checkup.
For now though we're going with the doctor's judgement and calling him Rintarou. I think he may very well be a boy though, 'cause little Rintarou can kick like a mini karate-master.