Confirmation of the death sentence on Seiichi Endo, 51, brings to an end a 16-year legal saga that has seen 189 members of Aum Shinrikyo indicted for crimes ranging from murder to abduction, the production of weapons and creating nerve gas.
Endo, a veterinarian who was the cult's "health and welfare minister," is the 13th follower of Shoko Asahara who will be hanged.
Even after the executions are carried out, the horror the cult left in its wake will linger. Renamed Aleph, the cult still had some 1,500 members as of April, while wanted posters in train stations show the two men and one woman still wanted in connection with the group's attacks.
Asahara, a nearly-blind yoga teacher, founded the cult in 1984, melding teachings from Christianity, Buddhism and Hinduism with interpretations from yoga and Nostradamus.
Declaring himself a reincarnation of Christ, he promised to wash away the sins of his followers and railed against conspiracies against Aum by Jews and the British Royal Family.
The cult recruited heavily from Japan's top universities, reaching out to young men who were socially inept and seeking to make friends, but who were also experts in engineering and the sciences.
Asahara stood in the general election of 1990 but, after failing dismally at the polls, the cult's activities took a more sinister turn.
Followers of Asahara had already abducted and murdered a lawyer assisting families to free their relatives from the cult, along with his wife and their infant son, before Aum purchased AK47 assault rifles and a Russian helicopter. It was reportedly attempting to obtain the components for a nuclear weapon and its chemists started manufacturing sarin and VX gas in 1993.
Eight people died in a June 1994 attack on a court hearing a case against the cult in Matsumoto and, when the cult realised that a raid on its compound on Mount Fuji was imminent, it went on the offensive.
In the rush-hour of March 20, 1995, five teams of cultists released sarin gas on trains in Tokyo, killing 12 people and injuring as many as 5,000 more people.
The raid on the compound revealed explosives, chemical weapons, biological warfare agents such as anthrax and Ebola cultures. Drug laboratories were producing LSD while strongboxes held millions in cash and gold.
Asahara's death sentence was upheld by the Supreme Court in September 2006.
