Xbox 360 sales have been rather low since the launch in Japan. In the week ending August 10th Microsoft sold a surprising 24,962 units and outsold the Sony PS3 (9,673) by far.
The reason seems to be the release of Bandai’s Tales of Vesperia that sold over 100,000 copies in the first week according to Media Create.

Like in the United States the Wii is still on top of the Xbox 360 and PS3, but both handheld gaming systems sold more than the Wii in that week.
Tales of Vesperia marks the first Tales RPG release in high-def with detail and graphics never before seen in the series.
Tales of Vesperia will be released in the United States on August 26th. There is a premium edition and standard edition available for pre-order on Amazon.com.
Via Edge.