Actress Mariko Kaga was born on December 11, 1943, in Tokyo. Her real name is Masako Kaga. She was scouted while attending Meisei Gakuen High School and made her debut as an actress in the 1960 Fuji TV drama "Tokyo Tower Knows." She appeared in "Tears, Lion's Mane Hair," released in 1962, and steadily built her acting career thereafter. However, by the time she turned 20, Kaga was exhausted by life in the entertainment industry. She canceled all her work for the next six months and traveled alone to France to study. Introduced to her by the owner of Chianti, a restaurant she frequented as a student, she thoroughly enjoyed life in Paris, hanging out with Yves Saint Laurent and François Truffaut. After returning to Japan, director Keita Asari invited her to appear in Shiki Theatre Company's "Ondine" in 1965. The performance recorded the largest capacity audience since the opening of Nissay Theatre, once again establishing her presence as an actress. She continued to appear in a variety of productions, winning the Kinema Junpo Best Supporting Actress Award in 1981 for her role in the film "Mud River." In 2005, she appeared in the TV drama "Boys Over Flowers," gaining popularity among young audiences. These achievements were recognized with the Tanaka Kinuyo Award at the Mainichi Film Awards in 2013, the Golden Glory Award at the Japan Film Critics Awards in 2014, and the Mizuno Haruo Award at the Japan Film Critics Awards in 2015. Kaga's impulsive personality and sharp tongue, contrary to her good looks, have earned her the nickname "little devil" since her youth. As the host of "Yoru no Hit Studio SUPER," which began airing in 1989, she repeatedly made controversial remarks, and at one point was dubbed the Japanese Brigitte Bardot. In 2004 she published her first essay, "Tongatte Honki," and in 2008 she published an expanded and titled paperback, "I Became a Pure-hearted Old Lady."

In her personal life, she gave birth to a baby girl in 1972, but the child died shortly after birth. In recent years she has been in a relationship with stage director Kiyohiro Makoto, with whom she is in a common-law marriage.