More than three-quarters of Japanese firms say the yen has declined to the point of being detrimental to their business, a Reuters poll found, with almost half of companies expecting a hit to earnings.

The results of the Reuters Corporate Survey are one of the clearest signs yet that much of corporate Japan is struggling with higher costs and worsening consumer demand caused by the yen's weakness.

The survey also showed almost 60% think the government should move quickly to restart nuclear reactors, evidence that higher energy costs — driven in part by the currency's slide — may be changing opinion on nuclear policy.