Rain Fall by Barry Eisler

Rain Fall is a mystery/thriller about a half-American, half-Japanese hitman named John Rain. John is a Vietnam veteran. His Japanese father died when he was a child, so his mother moved him to America to be near her parents. He became a special ops type while serving in Vietnam, and never really got over his experiences during the war.

After the war, John moved to Japan, where he took up a career as a hitman, specializing in making natural-looking hits. This first novel in the John Rain series starts with John (and his assistant Harry) tailing a potential hit. John has three rules about hits: he won't hit women or children, he won't hit secondary targets (e.g. someone whose death will affect the real target), and he won't work on hits unless he's the only hitter hired. When John believes his rules have been broken in the latest hit, he goes underground and starts an investigation of the man who hired him.

In addition to being a hitman, John is a major jazz fan with a particular liking for Bill Evans. Visiting a jazz club, John has a serendipitous meeting with a female jazz pianist (Midori) who is also the victim of his latest hit. While John is enjoying the set, he notices a man who was present at the hit, and determines that Midori is in danger.

The remainder of the book finds John and Midori searching for clues and killers while becoming romantically entangled.

This is an engaging read, and John Rain is an interesting character. At least three additional books have been written in the series. For more information, see:

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