I agree with Nai about drinking weak cordial or juice. Again its about blood sugar levels I think.

* Lemons - lemon juice, lemons in water etc. A friend of mind found eating them like an orange helped her. Like Nai said, it's really individual as to what will work and sometimes what worked early on stops working later.
* Dried ginger. (Easy to travel/pack)
* Not eating and drinking at the same time.
* Smaller meals more often.

You might not get m/s that badly. I was expecting it too and it has been around a little bit from time to time but nothing that knocked me about too badly. you escape it! Enjoy Japan