Shinkansens run on electricity. Oil is mostly in the manufacturing and plastics industry, unlike other countries where domestic consumption is a significant share. (Tokyo power sector is mostly thermal and nuclear.)
EDIT: these numbers appear to be old, since 2019 they’ve tuned reactors back on and stopped relying on LNG as much. I can’t find good numbers on recent data but in 2019 they imported more gas than any other country.
Fossil-fueled thermal power generation accounted for 71.7% of total electricity generated during the year [2021], down from 74.9% the previous year [2020]. Coal and LNG accounted for 26.5% and 31.7%, respectively, and both fossil fuels are on a declining trend. Nuclear power accounted for 5.9%, up from 4.3% the previous year.
I wonder why geothermal isn't big there. I'd naively assume that they could get a significant portion to their electricity from geothermal. Does anyone know what's preventing Japan from doing that?
Without knowing how good a geothermal resource they have, I imagine it is similar to what prevents it from being popular where I live where there is a fantastic geothermal resource: Economics, know how, FUD