Famitsu have reported on the first four days that Xbox One has been on sale in Japan and it's not a great read for fans of Xbox One in the land of the rising sun. Famitsu reports 23,562 units were sold (the bundled Titanfall achieving sales of 22,416 copies) in these four days, which pales in comparison with previous Xbox launches in Japan (Xbox 360 had 62,135 units sold in two days back in 2005) and recent launches of PS4 and Wii U (both selling over 300,000 units).
Given the downward slope Microsoft have been experiencing in Japan it's no real surprise to see Xbox One performing this poorly and with no major Japanese exclusives on the horizon beyond Scalebound it's hard to see them turning the trend around.