Japan has spent around 10 trillion yen ($64 billion) since last week propping up the yen, local media reported citing market estimates based on central bank data.
The market interventions reportedly began on April 30 when the Japanese currency weakened to near 160 yen per dollar, the lowest in almost two years.
Since then there have been several spikes in the unit, sparking speculation of further moves by authorities, and on Friday it was trading close to 157.
Atsushi Mimura, Japan's top currency official, on Thursday declined to comment, local media reported.
U.S. Treasury Secretary Scott Bessent was due in Japan next week to discuss currency issues and other matters, the Nikkei daily reported.
Bessent was then due to join U.S. President Donald Trump in China, the report said, citing U.S.- and Japanese diplomatic sources.
The yen has weakened on the back of the recent rise in oil prices as well as the gap between U.S. and Japanese interest rates.
The last time Japanese authorities intervened was in July 2024 as the yen neared 162 per dollar, spending some 5.5 trillion yen.
