Fūrin Kazan (風林火山) is the 46th NHK Taiga drama television series that began on January 7, 2007. It was aired throughout 2007, with the last episode aired December 16, 2007. Its official English title is The Trusted Confidant.

The story, to a large extent, was an adaptation of Yasushi Inoue's 1959 historical novel of the same title (published in English under the title The Samurai Banner of Furin Kazan). The four characters of the title, from left to right are wind, woods, fire, and mountain. The title is a reference to the war banner used by Takeda Shingen, which in turn was taken from Sun Tzu's The Art of War. It means "Swift as the Wind, Silent as a Forest, Fierce as Fire and Immovable as a Mountain."