A Clean Kill in Tokyo by Barry Eisler
I read this back in the early ’00s when it was called Rain Fall, my curiosity piqued because I’d read a rumor that Jet Li had optioned it for a potential movie. The Jet Li movie never came to pass, but it was turned into a live-action film in 2009 starring Kippei Shîna and Gary Oldman (which I haven’t seen). This is a satisfying enough thriller about a half-Japanese assassin who specializes in deaths that look natural (e.g., heart attacks). After his latest assignment, he gets mixed up with the daughter of his target, a Japanese shadow government, and his former colleagues at the CIA — as you do. Like most books in this genre, it’s nothing terribly deep or thought-provoking, but makes for some nice late night/weekend reading. Barry Eisler lived and worked in Japan for several years, which gives his writing a nice verisimilitude, though the samurai/ronin metaphors and references get a bit heavy-handed after awhile.