The Ninja novel was written in 1980 by Eric Van Lustbader and is a tale of revenge, love and murder. The author blends a number of known themes together: crime, suspense and Japanese martial arts mysticism. The book is divided into five parts, called "rings," as an apparent homage to Miyamoto Musashi's The Book of Five Rings. The book became a New York Times Best Seller. In North America, it contributed to the popularization of ninjas in popular culture. Source: Wikipedia (en)