Shigenobu Fusako, the former head of the now-disbanded Japanese Red Army militant group, was released from prison on Saturday.
The JRA was founded in 1971 in Lebanon by Shigenobu and others as a spin-off of the Red Army Faction.
The group advocated revolution through terrorism. It was most active in 1970s, and was involved in a series of terrorist attacks in collaboration with armed Palestinian groups.
JRA members armed with automatic rifles opened fire at an airport in Israel in 1972, killing and wounding about 100 people.
The group hijacked a passenger plane in 1977 and forced it to land in Dhaka, Bangladesh. The hijackers demanded that Japan release group members held in prison.
The government freed the members in what it called an extralegal response. This drew harsh international criticism that the government had yielded to terrorism.
Shigenobu was arrested in 2000 after covertly returning to Japan and staying hidden in Osaka.
In 2001, she declared that the JRA had been disbanded.
Police continue to seek the whereabouts of seven JRA members still at large.