9to5Mac reports that "the case packs a built-in Lithium-polymer battery that allows you to charge the iPad while in use. It also features a USB port, mini USB port, and Bluetooth for the keyboard. The case is available through Japanese retailer Rakuten for 5,980 yen (or roughly $75), so it could land in Rakuten's United States-based Buy.com in the near future."
You can also find the case on Amazon.co.jp but note that it only specifies support for the iPad 2, though the minimal size difference of the iPad 3 might mean it's compatible as well.
Read More [via 9to5Mac] [via Macotakara]