Tokyo police are intensifying their efforts against a series of scams where fraudsters falsely claim that old banknotes will become invalid due to the issuance of new currency notes for the first time in 20 years.

Four such cases have already been reported in the capital by Monday. A senior Metropolitan Police Department official warned, “This is a malicious fraud taking advantage of changes in the currency system. Please be cautious.”

Since March, four individuals in their 80s and 90s have been swindled out of a combined total of approximately ¥15 million ($92,800), according to police reports.