Last post (http://boxrec.com/forum/viewtopic.php?f ... apan+money)
As far as I understood (and even translating in other languages, and converting yen to USD) the peak of an estimated A class boxing match is maximum 3 million dollars, the average is ~1 million to less.
Source found - http://careergarden.jp/boxer/salary/
Yeah, it seems to pay well (at least for the champions or high level fighters in top bouts) for a country with a medium boxing culture, but not so prosperous like in the UK, which higher purses are average around ~3 million (USD) and in U.S with ~5 Avg (excepting rare cases like Mayweather's and few others bouts/superbouts of 20+ million).
That's it, I hope u guys enjoy