Nintendo of Japan recently announced a few new Wii U hardware accessories, most notably a bigger battery pack for the system's GamePad. A new 2,550mAh battery has double the power and can play for up to eight hours, but it requires a manual install.
One common criticism of the Wii U is its short GamePad battery life, lasting just 3-5 hours on a charge. Nintendo has long said the battery would be user-replaceable. This announcement is only for Japan so far, but with E3 just around the corner we may hear domestic plans soon.
Other hardware kit reported by Eurogamer includes a white version of the 32GB Wii U Premium, and a Wii Remote battery pack and charging cradle. The company also announced a new bundle with Nintendo Land, as that game hadn't been bundled with the system in Japan before.