Pokemon fans in Japan can at last grab their smartphones and set off outdoors in pursuit of monsters as ¡°Pokemon Go¡± debuted Friday.

After it launched overseas on July 6, the GPS-based smartphone game has already become a massive hit in more than 30 countries. The unexplained delay in releasing it in Japan left die-hard fans perplexed and itching to go.

¡°Pokemon Go,¡± a game that is free to download and play, uses the phone¡¯s GPS sensor and camera to guide players around streets and parks to find and capture Pokemon monsters. The characters are superimposed on a live camera image of the surrounding scenery, offering an immersion experience that many find addictive.