Seven members of a brainwashed doomsday cult were hanged yesterday in a sterile Japanese execution chamber for carrying out a deadly gas attack in 1995.

The Asian country is one of only two first-world democracies in the world, along with the US, to kill their own citizens.

Unlike the US, where execution dates are set in advance, prisoners in Japan are executed with very little warning and are told they are going to die on the morning of their execution — usually about an hour before.

The UN Committee against Torture has criticized Japan for the psychological strain this places on inmates and their families.

Condemned inmates in the country are executed by hanging — where their neck is swiftly broken using a rope and a trap door.

A blindfold and black hood are placed over the prisoner’s head before they are killed.

Three prison officers simultaneously press buttons to open the trap so it’s not clear which one is responsible.

Only prison officials and a priest are present.

How many people does Japan execute every year?

Between 2012 and 2016, 24 people were executed, according to the most recent justice ministry data.

Hangings are announced afterward. Since 2007, the justice ministry has released the names and crimes of those executed.

The annual number of those executed in Japan normally does not exceed 10. For example, from 1977 until 2007, the country never executed more than nine people in a 12-month period.

The seven people were executed at several facilities, the largest number executed at one time since 1998, when the justice ministry started releasing information on executions, officials said.

Those killed included the leader and six members of the Aum Shinrikyo cult that carried out a deadly sarin gas attack on the Tokyo subway in 1995, which killed 13 people.

What rights do Japanese death row inmates have?

Those sentenced to death can appeal up to the Supreme Court. The multiple Aum-related trials lasted more than 20 years.

Convicted inmates can seek a retrial even after a Supreme Court ruling, but this does not guarantee a stay of execution.

Several of those executed Friday may have had requests for retrials pending, Amnesty International said.

The law says an execution must take place within six months of the sentence being finalized by the courts, but in practice, it usually takes several years.

The justice minister decides the timing.

Does the Japanese public support the death penalty?

A 2015 government survey found that 80.3 percent of people supported the death penalty. That compares with 54 percent in the United States.

“I believe imposing a death penalty on those whose crimes are extremely grave and atrocious is inevitable,” Yoko Kamikawa, the justice minister, said Friday.

Anti-death penalty activists say a lack of information and increased interest in victims’ rights are partly behind the support.

In 2010, then-justice minister Keiko Chiba, who opposed the death penalty, signed off on two executions and opened an execution chamber to media for the first time, hoping to stimulate debate.

In 2016, a lawyers group called for the abolition of the death penalty by 2020, citing the possibility of wrongful convictions and international trends against capital punishment.

Before the recent executions, the last one in Japan was Teruhiko Seki, 44, in December 2017.

Seki was a minor when he killed four people — a 42-year-old corporate executive, the man’s wife, 36, their 4-year-old daughter and the executive’s 83-year-old mom.