I’m guessing he’s had at least one book written about him based on his career in Japan. At least two titles were released in the U.S., including Hideki Matsui: Sportsmanship, Modesty, and the Art of the Home Run (2007) and Godzilla Takes the Bronx: The Inside Story of Hideki Matsui (2004).
In 2006 I did a profile of Roger Kahlon, who served as Matsui’s translator, for Verbatim, a language magazine. Unfortunately, it’s not on-line (at least not for free).
Check out other great articles at Ron Kaplan’s Baseball Bookshelf.