David McNeill: Little light has been shed on these dark secrets in 350 years

Why is Japan, which uniquely prohibited the death penalty for 350 years, swimming against the global tide toward abolition?

Activists cite a lack of debate. "There is no discussion about this in the media," says Nobuto Hosaka. "Even in the Diet [parliament] the death penalty is something of a taboo because most lawmakers know the abolitionist cause is unpopular. It has become a vicious circle."

The gallows are shrouded in secrecy. When a group of ministers won the right to see the gallows six years ago, they were the first political delegation in three decades. Executions have been timed to coincide with Diet recesses to avoid protests from opposition MPs, prison guards are forbidden from discussing their work and until yesterday few ordinary civilians have ever set foot inside an execution chamber. The justice ministry never publicly releases the names of the people it kills. Still, a handful of former insiders have illuminated Japan's ultimate legal sanction and the people who carry it out.

Former death row prison guard Toshio Sakamoto wrote a book about his experiences. He says that prison guards are rotated every three years to prevent them building up feelings of empathy with their charges. Like the prisoners, the guards are told on the day of an order when an execution is to be carried out.

Discussing the details of the work or whether they have actually put a rope around somebody's neck is "taboo", says Mr Sakamoto, who claims the stress of the work sends some to psychiatric hospitals. "Nobody talks about the rights of the men who do this," he says. "No matter how psychologically strong they are, guards get mentally and physically exhausted serving inmates on death row because it is truly cruel."

Former prison-guard-turned lawyer Yoshikuni Noguchi says on the morning of an execution two burly guards strong enough to control a resisting man take the condemned prisoner by each arm and lead him to a concrete room. The condemned have just minutes to get their affairs in order before facing the noose because they are not told about the execution until the same day. A Buddhist or Christian altar, the prison warder and a curtain concealing the other half of the room are among the last sights he will see. The curtain is pulled back to reveal a glass-encased room and the prisoner is asked if he has any final words.

"It is not unusual for the men to say thanks to the guards or apologise for causing them trouble," according to Mr Noguchi. Mr Sakamoto says he has seen men being dragged kicking and screaming to the gallows, calling out for their mothers.

Inside the room, three guards wait before three buttons. The prisoner is handcuffed, hooded and bound at the feet and a 3cm-thick rope is slipped around his neck. The guards push the buttons but do not know which one has been rigged to open the trapdoor beneath the prisoner's feet.

A doctor waiting with a prison official checks the heart of the hanging man. They wait for five minutes to make sure of death and then take the body down, put it in a coffin and ship it to a prison morgue. In most cases, says Mr Sakamoto, the bodies will never be picked up.