water
Oil is the main one
sushi is the biggest scarce resource in japan since chairmen mow outlawed the fishing of public sewage lines and burned the rice fields.
Japan, like Britain, is made up of islands.
because it provides the nations food
Doolittle's raid on Japan was an effort to damage Japan's resource, as well as to make it known the US would not sit back and take an attack without retaliating.
There are a number of disadvantages of silk farming. Some of them include lack of a ready market, limited resource to facilitate this type of farming and so much more.
Oil, metals, or natural rubber.
the lack of any formal warning by Japan.
the surrounding ocean
Japan does not have enough of any economic resources to support their nation; which is why they expanded to colonization (conquests) from the 19th century culiminating into WW2. Their only resource is quality production. What Japan produces, they must live with; Re-supply can ONLY come by IMPORTATION. Consequently, when a product is built, it must be as near perfect as possible in order to survive usage.
In some geographies, yes, diamond is a major resource.
a failing economy and a growing lack of faith in democracy.