Hey Japan is awesome. I lived there for 2 years and I have some experience.

If you are prone to thrush, take some canesten with you because getting treatment for thrush in Japan is not fun. Believe me, you don't want to go to a gyno in Japan (unless you want a doctor plus 5 nurses probing your privates).

Don't eat the convenience store (konbi-ni) food. It's fresh enough, but pretty gross.

It's freezing cold in Japan right now and snowing a lot. Rug up!

Even though it's fresh don't eat sushi or sashimi while pregnant. There are a million and 1 other meals to delight in so don't worry about it.

Do not, under any circumstance, eat fugu!