What does Japan import most?

The "degree of dependence on imports" in 2000 provides the answer to the question.
The following is the ranking of items where domestic consumption is mainly dependent on imports.

1. uranium 100.0%
2. iron ore 100.0%
3. bauxite 100.0%
4. copper ore 99.9%
5. crude oil 99.7%

Compare the figures shown above with those of the degree of dependence on exports in answer to the previous question.
This brings out the fact that Japan's trade consists of what is called "added-profit trade," in which it sustains itself by importing energy sources and raw materials, processing them into products, and exporting them to the world.