She left Japan in 1971 to travel around Europe where she came in contact with the Popular Front for the Liberation of Palestine (PFLP), and set up the what was later to be called the Japanese Red Army in Lebanon in February of that year. She was placed on the Metropolitan Police Department's international wanted list for the seizure of the French Embassy in The Hague, the Netherlands in 1974. Her goal was to establish bases around the world and to start a revolution in Japan.
She is also known by the surname Okudaira, which she registered herself under in Japan after faking a marriage to Takeshi Okudaira, another Red Army member who died during an attack in Tel Aviv.
She was arrested in Osaka in November 2000 outside the Takatsuki Kyoto Hotel where she was staying at the time. The arrest came as somewhat of a surprise since she had been evading Japanese authorities for 30 years and was believed to be living somewhere in Lebanon, although she had been living in Osaka since July 2000 using her friend's name. After her arrest, she shouted to reporters "I am determined fight on."
She is on trial on various charges, including leading the Japanese Red Army seizure of the French embassy in The Hague in September, 1974. In that incident, three Red Army members took 11 people hostage and forced the government of France to release one of their members.
She has one daughter, Mei Shigenobu, whose father was Palestinian. She was not citizen of any country until March 2001, when she became a Japanese citizen. She only saw her mother at most two months out of the year when she lived in Lebanon, but called her mother a logical woman and that she "never raised her hand or raised her voice but she had a very good way of convincing you if you were wrong". As a child, she attended a strict Muslim school, although she states she is no longer a Muslim. She visited Japan for the first time in her April 2001. She had gained a small amount of notoriety with her controversial visit of a public school in Kanagawa prefecture near Tokyo on December 15, 2001. She apparently gave a talk on Arab culture and food, but the Israeli embassy in Tokyo sent a complaint to the school, stating the talk was politically biased when she spoke of the Palestinian Authority. In 2002, she lived in Tokyo and worked as an English teacher in a cram school.
During her trial hearing in April 2001, Shigenobu stated that she was disbanding the Japanese Red Army, and said she would continue her fight through legal means. In May 2001, her book Ringo-no Ki-no Shita-de Anata-wo Umo-to Kimeta (I decided to give birth to you under an apple tree) was published which was written as a message to her daughter.