Microsoft has announced (translation) that it will release a standalone 250GB hard drive in Japan later this year. The drive – which carries a price tag of ¥15,540 (~$170) – is set to be released on March 11. On the same day, the company will also be releasing the Wireless Controller Game Pack and the Xbox 360 Wireless N adapter.
This will mark the first time that Microsoft has released the 250GB hard drive as a standalone product. Thus far, the 250GB model has only been available as part of certain bundles such as the Modern Warfare 2 bundle released in 2009. Previously, Microsoft's Albert Penello noted Microsoft didn't have any specific plans to release the 250GB drive by itself, though he did note the possibility. While this particular drive is currently slated only for Japan, it seems likely that other territories will follow.
We've contacted Microsoft regarding any North American or European release plans and will update this post with any new info.