Masako was born Masako Odate in Shibuya, Tokyo, the only daughter of Sue and Kazu Odate. Raised in Naka-ku, Yokohama, while in junior college in 1976 she auditioned for the lead role in Nihon TV's drama Ai ga miemasu ka. Chosen from 4,000 applicants, she dropped out of school to pursue an acting career, playing the part under her real name Masako Odate. Masako's mother initially objected to her choice of career and requested that she not use the Odate family name if she gained further work. In 1977, she changed her name to Natsume. In 1977, she was chosen to represent Kanebo Cosmetics, achieving great popularity after appearing topless as the "Kooky Face" girl in an ad for sunscreen. This popularity led to her recording a song later that year called "Oh! Cookie Face". Many bit parts and a few leads in movies followed but she continued in television. In 1978-79, she played the male part of Tripitaka in the 1970s Japanese TV program Saiyūki, which proved popular in many English-speaking countries in the 1980s, when dubbed by the BBC and titled Monkey. Masako won the part as she had matched contemporary descriptions of Sanzō-hōshi's appearance more closely than male actors who auditioned. Masako made her stage debut with the Tokyo-Takarazuka Theater Company in 1980 in the play "Kikaishi Naporeon No Taishoku". Specialising as well-bred but shy heroines in her movies, she was regularly criticized by the public and media for her poor acting. However, this changed in 1982 after appearing as an ambitious and immoral woman in the TV drama Shousha and as the daughter of a Yakuza leader in the movie Onimasa. One of her lines from this movie, "Don't you look down on me!", became a very popular catchphrase in Japan. She won the award for best actress at the 8thHochi Film Award for The Catch and Time and Tide.
In 1997, Canon produced a television commercial for a copy machine, featuring her photocopied images, which offered 100 free compilations of the images in a book. Canon received 230,000 applications. Masako Natsume picture books and calendars are still popular in Japan today. In 2007, TBS broadcast a documentary on Masako's life entitled Himawari – Natsume Masako 27-nen no shōgai to haha no ai based on the book Futari no Masako written by her mother, Sue Odate. Yagi Yūki played the part of the young Masako and Nakama Yukie portrayed her as an adult.
