Based on a popular serialised novel by Ayako Miyagi, the story depicts the spiritual recovery of a woman who returns to her father's home in Okinawa after her boyfriend's death.
Also in the cast are Kuranosuke Sasaki as the father, Seiji Fukushi and Misato Tanaka. Nagasawa also starred in 2004 tearjerker megahit Crying Out Love, In The Center Of The World.
The film is directed by Yosuke Nakagawa. Shot in cinemascope, Gunjo will feature numerous underwater scenes and depict the exploits of Okinawan pearl divers. Gunjo wrapped principal photography on August 5 and is set for 2009 release.
Fox plans to distribute the film internationally and is aiming for a slot at next year's Berlin film festival.
The news follows Fox International Productions' announcement at this year's Cannes film festival of a Japanese remake of Alexander Payne's Sideways, produced in partnership with Fuji TV. The only local production Fox was previously involved in was black comedy Out, produced in 2002.
Along with Germany, Russia and India, the studio is targeting Japan as a key territory for locally produced and distributed content. Until now, Warner Brothers and Sony Pictures have been the most active in production and distribution in the territory, with Universal close behind.
Fox Japan is also distributing Masayuki Ochiai's remake of Thai horror film Shutter this September.