Variety Asia Online is reporting that another piece of the puzzle has been added: Ken Watanabe has joined the cast. No details are offered about the role he will play, though the article fleshes out the plot a little. Referring to the character that will be played by Cusack (now confirmed to star), the article states: "While trying to solve the murder [of his friend], he falls in love and discovers a much larger secret that his own government is hiding." Hossein Amini wrote the script; he was nominated for an Academy Award for his work on The Wings of the Dove, and also adapted Jude as well as the more recent Killshot.
Watanabe has great presence; he shot to prominence opposite Tom Cruise in The Last Samurai and was memorable in both Batman Begins and Letters from Iwo Jima; he also received kudos for his work as a businessman beset by Alzheimer's Disease in Memories of Tomorrow. During the time period covered in the upcoming film, Shanghai was occupied by Japan, but, as noted above, we'll have to wait and see which part the Japanese-born Watanabe will play. Production is expected to start this spring in Shanghai. Watanabe was also recently cast in Cirque du Freak, which rolls this month, but I presume the filming schedules are compatible.