The Argentine pontiff said last Wednesday that he would visit Japan in November, becoming the first pope do so since John Paul II nearly 40 years ago.

During his stay in the country, Francis reportedly plans to visit Hiroshima and Nagasaki to pray for the victims of the 1945 nuclear bombings, which killed some 220,000 people instantly.

"I believe he will have sympathy for the movement to abolish nuclear arms," Keiko Ichikawa said after attending her first mass since the pope announced his trip to Japan, home to some 450,000 Roman Catholics.

"I hope the pope's visit will be an opportunity to encourage the movement," the 77-year-old told AFP.

Francis has repeatedly voiced a desire to visit Japan and wanted to work as a missionary there in his youth but abandoned the plan after a lung operation.

In January of last year, Francis issued a harrowing photograph taken in 1945 showing a young Japanese boy carrying his dead brother.

The child, carried on the boy's back, was killed when the United States dropped a nuclear bomb on Nagasaki.

Francis, who has often spoken of the dangers of nuclear weapons, had written on the back of the image just four words: "The fruit of war".

According to local media, the pope is also considering visiting the Fukushima region, which was hit by a massive tsunami triggered by a 9.0-magnitude earthquake in March 2011.

The high waves killed around 18,000 people and swamped the Fukushima nuclear plant, sending its reactors into meltdown and leading to the world's worst nuclear disaster since Chernobyl.

"We also have a great suffering in Fukushima due to the nuclear reactor accident," said Yuko Honma, a 82-year-old Catholic nun.

"I hope he will have a chance to visit there too" and encourage disaster victims, she added.

Authorities have been working to rebuild the region, about 240 kilometres (150 miles) north of Tokyo, although areas near the crippled plant remain uninhabitable because of radiation dangers.

During his trip to Japan in 1981, Pope John Paul II visited Hiroshima and Nagasaki. He also held a mass at a Tokyo baseball stadium, inviting some 35,000 believers.