Slash and earn: mystery benefactor leaves banknotes in toilets across Japan

Hundreds of civil servants across Japan have visited their office lavatories to spend a penny in recent weeks - and emerged £40 better off.

Police are scratching their heads over the identity of the mystery benefactor who is thought to have left more than 400 packages, each containing a 10,000 yen note, in men's toilets at local government offices across the country.

When the packages first appeared at the end of last year they were dismissed as a prank, but by today the number had grown to 425, with dozens appearing in the past week alone.

The motive behind these apparent random acts of generosity is not clear. Each note is wrapped in Japanese washi paper with the characters for "remuneration" written on the outside, and comes with a message written in a sweeping calligraphic style urging its finder to use the cash "for self-improvement".

"Do only good deeds," the message reads. "Do not think of evil."

Handwriting experts believe the notes were penned by someone with strong religious beliefs. The steady deterioration in the quality of the handwriting over the past few weeks suggests he may be a terminally ill man making one last philanthropic gesture.