Question

Which region is called the rust belt of japan?

Answer 1

Hey mate here is your answer.....
These are Shikoku Islands.

Hope it helps★

Answer 2

Shikoku Islands 
The Manufacturing Belt was called the Rust Belt in the latter decades of the 20th century because the word that describes the deterioration of iron into rust was an appropriate name to give to a region where the iron and steel and related industries were in great decline.