The contributing factor you ask? Well, actually there’s not just one, but quite a few. For one, the recent price cuts on all Xbox 360 systems in Japan must’ve been quite a helping hand. Secondly, the Premium system saw an increase in HDD space, from 20GB to 60GB, with no change to the price. Thirdly, Japanese retail stores finally got their new hardware shipments, following weeks of shortages. Last but not least, Square Enix’s Infinite Undiscovery hit store shelves and made one hell of a splash, ending up being the best selling Xbox 360 game in Japan with 86,708 units sold in its first week.