The yen has no fractional units (anymore), so when I added support for that currency but continued to use the same format string as all the others, prices like ¥1000.00 looked unnatural.
The historical subunit of the yen is the "sen" (銭), which you often seen mentioned in prewar books. Postwar inflation made sen-denominated currency obsolete, but...
[A bit of googling also turns up the "rin" (厘), which is a thousandth of a yen...]
