Via Eido Inoue's Google + stream. Here is a direct link http://nexus-premium.com/
I saw this at my local docomo shop today: the Samsung's Galaxy Nexus SC-04D Premium Campaign.
From February 1st to March 31st 2012, those who have purchased/own a SC-04D* can receive both a "Google Original Rear Cover" and a "Pocket Charger 01" (both pictured in the leaflet) as a set present!
First come, first served. Limited to 20,000 applicants. Restrictions apply. See rules at your local docomo shop for details.
* Sorry, the "Global Model" is not eligible. You must have a Japanese Docomo SC-04D variant of the Galaxy Nexus and live in Japan.
To apply, go to a docomo store and use the standard browser on your SC-04D phone and input the QR code / URL.