Reuters reports:
Japanese police have been scratching their heads in bewilderment over the country's latest counterfeiting trend -- fake bills that cost more to make than their face value.
...
"Police suspect a techno-maniac is involved," the Asahi said.
...
The fake bills are made by replacing the middle strip of genuine notes with a color photocopy, and securing them with tape.

A Soviet detective would figure this out in a second - those people are using color copiers at work which cost them nothing. "Techno-maniac". Hah. In Soviet times there were cases where people would pour out wine and soft drinks out of bottles stolen at work to get the deposit.