You are considered a California resident until you change residency to another state - which will not happen if you move to Japan. However, when you file your federal return, you can deduct up to $80,000, I think. (I think the foreign income deduction form is form 2555.) Hopefully, you can then use the amount of adjusted gross income from your federal return (amount = zero) and put that amount (zero) on the line for adjusted gross income on your state return. That should work, so you do not have to pay California taxes while in Japan.
DO NOT stop filing federal AND state returns while you are in Japan. I did not, for over ten years, and then I came back to the states. I had to go back and file all of those past returns, and pay all penalities. It was a nightmare.