Thanks for the heads up, OP.
The exchange rate sucks so hard this is NOT a deal to people in the US looking for a deal on games they could buy in their own region.
For people with a Japanese account, you get rewards for buying anything between the 7th and the 20th. At the end, if you've spent a total of X you get Y returned to your account.
500 - 1,499 yen = 100 yen
1,500 - 2,499 yen = 300 yen
2,500 - 4,999 yen = 500 yen
5,000 yen + = 1,000 yen