A finance ministry official told Reuters discussions were under way about the proposed amendment, saying he could not provide further details.
The revision "presumably enables the government to apply the law to crypto-asset exchanges like banks and oblige them to scrutinise whether their clients are Russian sanction targets," said Saisuke Sakai, senior economist at Mizuho Research and Technologies.
Following the invasion of Ukraine, the Japanese government has slapped asset-freeze sanctions on more than 100 Russian officials, oligarchs, banks and other institutions. Japan has also banned high-tech exports and revoked the most-favoured nation trade status for Russia, which calls its actions in Ukraine a "special military operation".