"a well-known male Japanese actor in his late 40s to late 50s who speaks English" to come on board as a mysterious character named "Moreau".Francois Chau (aka Marvin Candle from the Dharma videos on LOST) - he is Cambodian, not Japanese. Although, that didn't stop him from playing the head of Chinatown in The Chicago Code (also on FOX...)
However, in my opinion, I think it would be great to get Ken Watanabe. He played Mr. Saito in Inception, and of course costarred with Tom Cruise in The Last Samurai. He's Japanese, and the right age (51).
Who do you think should play "Moreau"?
Another good option, would be Hiroyuki Sanada, who played Dogen in the final season of LOST. He is also Japanese and 51. Coincidence?