Japanese composer Karen Tanaka (b. 1961) began piano lessons when she was four years old. After studying French literature, she entered the Toho Gakuen School of Music to study composition with Akira Miyoshi in 1982. During her studies she won composition prizes in Europe and the Japan Symphony Foundation Award.

In 1986 she moved to Paris, where she studied composition with Tristan Murail and worked at IRCAM as an intern. She received the Gaudeamus Prize at the International Music Week in Amsterdam in 1987 for her piano concerto Anamorphose, and she wrote Hommage en cristal on commission for the Norwegian Chamber Orchestra after studying with Luciano Berio in 1990-91.
Later works, such as The Song of Songs, Night Bird, and Metal Strings, took Tanaka's musical language in new directions using the latest technology and reflecting different aspects of contemporary culture.

More recently, her love of nature and concern for the environment has influenced many of her works, including Frozen Horizon (written for BIT20 in Norway), Water and Stone (commissioned by Radio France), and the tape piece Questions of Nature.

Guardian Angel was commissioned by New York's Music From Japan for their 25th Anniversary Gala at Carnegie Hall, and was premiered there by the Brooklyn Philharmonic, conducted by Paul Lustig Dunkel, November 9, 2000. "Guardian Angel was inspired by a passage in the Old Testament from Exodus 23:20: 'Behold, I send an Angel before thee, to keep thee in the way...'," Tanaka says. "After reading the passage, an image of angels, fragile and surrounded by beautiful illuminations, appeared in my mind, overlapping between Biblical times and our present time. My intention was to realize my image of angels with sounds, sent to guard us along the way." The piece is scored for clarinet, percussion, harp, and strings.