Capcom said Wednesday Monster Hunter Freedom 3 has shipped 4 million units in Japan in its opening month, bringing total shipments of the action RPG series to 17 million units.

The Osaka-based publisher said Monster Hunter Freedom 3, which has so far released only in Japan, achieved the same shipments in one month that 2008's Monster Hunter Freedom Unite reached over the course of two years.

Capcom claimed the sales of Monster Hunter Freedom 3, released December 1, make the game the "fastest selling title in PSP history."

The company expects the title to be a contender for Capcom's top-selling game within Japan for all of fiscal 2010, ending March 2011, as sales continue to be "favorable."

Capcom announced last month that the game shipped 2 million units in its first week of availability in Japan, and 3 million in about three weeks.

While the franchise is a hit with Japanese gamers who are drawn to Monster Hunter's connectivity and co-op play, the series is less popular in Western markets. A North American and PAL release for Monster Hunter Freedom 3 is yet to be announced.

The last Monster Hunter game that shipped for Western audiences was the well-reviewed Monster Hunter Tri for Wii, which launched in April last year in North America.