The Tokyo Police are flummoxed by the envelopes of 10,000 yen ($82) bills popping up in toilets in government offices.

The bills are individually wrapped in traditional Japanese "washi" paper with the word "remuneration" scribbled in ink. Each packet has a formal handwritten letter which says that the giver hopes that the money will be "used for your pursuit of knowledge". Since April, over $32,720 has been found in such envelopes. The police wonder -- is it an elderly man nearing death or just a prankster.