I would avoid (fish) sushi or sashimi (if you are into it that is) if I was you. There are loads of yummy Japanese dishes that you can have instead!

Having said that the hygeine standards in most sushi places in Japan exceeds ours here!

Be mindful of things like iced coffees and the like as the Japanese often put heavy cream in them instead of milk (and I don't know whether they pasturise!).

Many of their softdrinks are "energy drinks" with guarana and caffeine and the like (somewhat different to our version of sprts drinks) - so you may wish to stick to the more common drink varieties!

Japan is awesome though and you will have an amazing time!