Rockman DASH: 5tsu no Shima no Daibouken!

Release Information
Rockman DASH: 5 Island Big Adventure was first released in February 2008 to Japanese public via the I-mode Internet service, which requires a 315 Yen monthly fee (including taxes). The game includes five total islands, the first two of which were available upon its initial release. Afterwords, the other areas were released as downloadable content at regular intervals.

Below is the game's release information and release schedule:

Overview
Rockman DASH: 5 Island Big Adventure (ロックマンDASH 5つの島の大冒険!) is a Japanese game from the Mega Man Legends series released in 2008 for mobile phones via the I-mode Internet service, a subscription service that costs 315 Yen per month (including taxes). The game has a total of five islands, each with seven areas to explore. Mega Man and friends must explore them in search of treasure and to uncover their secrets.

The graphics engine used in the game is very similar to that used in Mega Man Legends and Mega Man Legends 2, however the game has a more polished look to it (less rough edges, sharper graphics, etc.). Most of the characters from the previous games have returned in this adventure, and there are many new (and some familiar) enemies for Mega Man to face.

Capcom has yet to announce any plans to release the game outside of Japan, but it does not seem unlikely that they will do so. In February 2009, it was discovered that Square-Enix plans to release their previously exclusively Japanese mobile phone sequel to Final Fantasy IV, entitled Final Fantasy IV: The After, in Europe and North America as WiiWare. With demand for another Mega Man Legends game so high, it is possible that Capcom will follow Square-Enix's example.