A rare joint U.S.-Japan intervention has raised the stakes on traders betting against the yen, but analysts are doubtful speculators will be kept at bay without tighter monetary policy.

Washington's decision to join Japan in supporting the battered yen has prompted questions over what motivated the rare coordinated intervention.

The Kumamoto prefectural government said at least 34 people were killed in the powerful earthquake that hit southwestern Japan earlier this week.

U.S. and Japanese officials confirmed that the Treasury Department had moved last week to prop up the currency, which had been trading near four-decade lows.

Almost no other country in the world is rocked by such frequent and damaging earthquakes as Japan, which sits on the boundary of four tectonic plates.

A major earthquake in Japan's southwest killed at least 13 people and left several injured or missing after a shopping center and a paper mill were heavily damaged.

Soldiers and emergency workers combed through a badly damaged shopping mall and collapsed houses looking for trapped survivors Wednesday after a powerful earthquake that killed at least 18 people, including a foreigner,

Japan's three major financial groups have posted record net profits for the three months to June, partly thanks to a boost in income from higher interest rates.

The former prison also served as a filming location for the second season of Netflix's Japanese series "Alice in Borderland."