The Japanese Pokémon Centers have announced that a Master Ball (マスターボール) will be distributed at the Tokyo, Yokohama, Nagoya, Osaka, Fukuoka and Sapporo Pokémon Centers to celebrate the release of the Official "Learn to Know the Pocket Monsters Black and White National Zukan" Book (ポケットモンスターブラック・ホワイト公式 ポケモンぜんこく図鑑がよくわかる本). It will be distributed from November 19th, 2011 until December 3rd, 2011. Players of the Japanese versions of Pokémon Black and White can receive the gift.


Starting December 17th, the Pokémon Centers will be selling small monster ball straps. Each ball can be opened, and contains a folded-up AR marker for use with the Pokédex 3D. Click here for the imageboard thread to see all the different monster ball straps. They will sell for 500 yen each.


Sources: http://www.4gamer.net/games/104/G010490/20111118037/ and http://www.pokemon.co.jp/info/2011/11/111118_p05.html