The fourth daughter of Aum Shinrikyo founder Shoko Asahara recently expressed regret over the sarin nerve gas attack the doomsday cult carried out on the Tokyo subway system on March 20, 1995.
The gassing 20 years ago killed 13 people and left more than 6,000 injured.
"I feel sorry to be alive" when thinking about the victims, the 25-year-old said in recent interview.
With the babbling 60-year-old Asahara, whose real name is Chizuo Matsumoto, on death row for masterminding the subway attacks and other crimes, she said: "My father should absolutely be executed."
The daughter, who has severed all links with the cult and lives away from her family, said that she "felt half sad and half relieved" when Asahara was arrested at a cult facility in Yamanashi Prefecture about two months after the attacks.
But she also admitted to earlier believing in her father's innocence after being told the cult was being subjected to religious persecution.
She began looking into the circumstances behind the attacks after Asahara was sentenced to death at the Tokyo District Court in February 2004, when she was 14. In her late teens, she recognized her father's role in the crimes and eventually renounced her ties to the cult.
She also said she attempted to kill herself several times after being bullied at school and fired when her employer discovered she was Asahara's daughter.
As for the reported attempt by Aleph, Aum's successor group, to make use of her brother, she said she "cannot stand" the idea of him being embroiled in the group.
Asahara and his wife, who was a senior member of the cult, have four daughters and two sons.