After the long waiting, Niantic today released the official Japanese version of the Pokémon GO in the Google Play and the AppStore. The game is the same as in the other regions but Niantic prepared an independent background system for Japan.
The game is a free to play like in anywhere but you can but additional items (for example balls) for real money. Yesterday NISC already published a PDF guide in Japan for the future GO players. Please pay attention on the street around you and have a great time!