The vast majority of Japanese companies expect the yen to firm against the dollar by year-end, a Reuters monthly poll showed on Thursday, suggesting further weakness in the local currency could catch businesses off guard.

The yen's downturn this year, which accelerated in recent weeks, has burdened households with higher costs of everything from food to fuel. The rapid declines have also raised alarm among big companies and policymakers, making it difficult for companies to plan for the future.

The currency has lost about 20% versus the dollar since the start of this year, hitting a fresh 24-year low of just shy of ¥145 last week. The yen has been hammered against the dollar due to the growing gap between U.S. and Japanese interest rates.