You don't really need any Japanese going there, pretty much all the signs in the cities are in 4 languages (jp,cn,kr,&en). Learn the language if you like it or want to learn it and use it when you go if you want to, but don't let that stop you.
I say, just make a decision and carpe diem. If it's important to you, do what you need to make it happen.
Thanks, I also see that they put pictures on restaurant menus so you can just point to order. Good advice, 'Seize the day'. I haven't hear that since high school Latin.