Disclaimer: I think that Japan has too high a debt. But saying "These costs will significantly rise with a lower yen, therefore the product prices will catch up

Disclaimer: I think that Japan has too high a debt. But saying "These costs will significantly rise with a lower yen, therefore the product prices will catch up and they not be competitive anymore on the global market in a couple of months" is mathematically wrong. Japan imports raw material, adds value with labor, and re-exports that material. The price of the raw material, if it doesn't change between importing and exporting it, is totally transparent. But with a lower yen you have actually lowered the cost of Japan's labor. So, yes, devaluing your currency makes your labor more competitive - you just made your workers less expensive. The downside? Your workers are less expensive - ie, poorer.