As Tokyo stocks tumbled further Friday, dragging the Nikkei average to its first close below 15,000 since October 2014, economists asked: Is Abenomics out of options?

Prime Minister Shinzo Abe has relied heavily on ultra-aggressive monetary easing to weaken the yen and boost exporters' profits in his quest to end deflation. The campaign was a boon for the stock market, raising prices, benefiting rich investors and cementing Abe's power base.

The resurgent yen and the stock plunge will be painful for his administration, which has failed to come through on structural reforms, but many say the more serious issue is the Bank of Japan's helplessness.