Japanese shares shed their previous session's gains to close in the red following a weak trading session on Tuesday.
The Nikkei 225 closed down 200.09 points or 0.3% at 66,734.24.
The decline tracked losses among Asian peers amid escalating tensions in Iran.
According to media reports, the US bombed radar and drone sites in Iran after the latter shot down an American drone over the weekend.
It is also reported that Iran has suspended communication with the US regarding ending the war, due to Israel's escalating military strikes in Lebanon.
On the corporate front, Sumitomo Metal Mining's (TYO:5713) profit attributable to owners of the parent surged 969.3% to 176.29 billion yen in the fiscal year 2025 ended March 31, from 16.48 billion yen a year ago.
Ricoh (TYO:7752) and its Asia-Pacific subsidiary have closed the acquisition of Global Vision Multimedia, a specialized AV and multimedia integration firm, following strategic partnership talks that began in January, according to a statement on Ricoh's website on Tuesday.