Rise in fraudulent emails against Japanese banks indicates wider trend.
Phishing attacks against non-English speaking countries are on the rise, according to the security company Kaspersky Lab.
Although most phishing emails looking to steal bank or payment data are still written in English, researchers have seen an increase in the number of fraudulent emails written in foreign languages, with Japanese banking customers a particular target.
Tatyana Shcherbakova, anti-spam analyst at Kaspersky, said victims were told their data might have been leaked, and as such "the bank system security had been updated to protect their accounts".
The phishing message then told them to follow a link to a website to enter their banking credentials, with the customers warned that their accounts would be blocked if they did not comply.
"The information entered in the phishing form was sent to the fraudsters who got access to the personal account of the victims and could control their money via the online banking system," she added.
Kaspersky also reported that a month later a similar message discovered by the firm had been made more plausible by using a spoofed email address and a more "genuine" link.
"Only a careful user would spot the difference," Shcherbakova said.