Well the Xbox One (just like the Xbox 360 was) is not the best sold console in Japan. Not the best? The console always stays at the last position in the Japan Chart with less than 100 sold units while the top console can get more than 10 000 and 15 000 sold units.
To raise a little bit the selling numbers of the latest Xbox console, Microsoft Japan going to starts on September 1, 2016 a price cut campaign with the 500 GB and the 1 TB version Xbox Ones. You can get them until December 31, 2016 with more than 10 000 Yen OFF which means the 500 GB version will be available for 29 980 Yen (with tax). The original price of the console is 36 729 Yen (with tax) so it is a great deal.