TOKYO – As Japan marks 80 years since its surrender in World War II on Aug 15, 1945, the country’s collective memory of its role in the global conflagration – and the catastrophic defeat it suffered – is fading fast.

The voices of living veterans, such as 95-year-old Hideo Shimizu, and atomic bomb survivors, like 86-year-old Michiko Yagi, are fast disappearing.

How Japan will remember its imperial past and the war’s influence on the nation’s psyche is now becoming a pressing concern.

Ms Yagi, a hibakusha who experienced the devastation of her native Nagasaki on Aug 9, 1945, counts her family – her mother and four siblings – fortunate to have survived the blast, although they endured prolonged bouts of debilitating diarrhoea in its aftermath.

Hibakusha is the term used to refer to survivors of the atomic bombings of Hiroshima and Nagasaki.

“Historically, Japan certainly has made mistakes, and those mistakes are our burden to bear as wartime aggressors,” Ms Yagi told The Straits Times.

“It is our responsibility to remember, to convey our experiences, to fight for peace and to lobby for a world without nuclear weapons,” she said, expressing her deepest wish for Nagasaki to remain the last city on earth to suffer the horrors of an atomic bomb.

“The youngest hibakusha is now 80, and soon there will not be many of us left. Looking at the perilous state of the world today, I honestly feel really scared.”

Ms Yagi is one of just 99,130 remaining hibakusha, whose average age now stands at 86 years, according to official figures released on March 31. For the first time, their numbers have dipped below 100,000.

The atomic bomb was a weapon of unprecedented destructive power that obliterated the cities of Hiroshima and Nagasaki.

Then Emperor Hirohito, in a nationwide radio broadcast announcing Japan’s surrender at noon on Aug 15, 1945, starkly described it as “a new and most cruel bomb”, acknowledging that “the war situation has developed not necessarily to Japan’s advantage”.

In the present day, a year-long series of war memorial events culminated in the Memorial Ceremony for the War Dead on Aug 15, although the surrender documents were formally signed only on Sept 2, 1945.

At the annual ceremony, where a minute’s silence was observed at 12pm, Prime Minister Shigeru Ishiba was the first leader in 13 years to express “remorse for the war” in his memorial speech.

“We must never repeat the horrors of war. We must never again err on the path we take,” Mr Ishiba said. “We must now deeply engrave in our hearts the remorse and lessons of that war.”

He added: “No matter how much time passes, we will continue to pass on the painful memories of war and our resolute pledge to never wage war again across generations and continue to take action towards lasting peace.”

This pacifist message was reiterated by Emperor Naruhito, who said: “Looking back on the long period of post-war peace, reflecting on our past and bearing in mind the feelings of deep remorse, I earnestly hope that the ravages of war will never again be repeated.”

Elsewhere in the region, Japan’s surrender was marked with both Koreas commemorating National Liberation Day on Aug 15. China, meanwhile, is set to showcase its military strength at a “Victory Parade” on Sept 3.

What is evident is that 2025 is a crucial milestone anniversary, imbued with the added urgency of the advanced age of the last surviving first-hand witnesses to the war’s horrors.

Japan’s surrender and its subsequent occupation by the US from 1945 to 1952 irrevocably shaped the nation’s psyche. The 1947 Constitution, drafted by the US, remains the oldest unamended supreme law in the world and set Japan on the path of pacifism.

The Emperor, once a godlike figure, was reduced to a ceremonial figurehead.

The battle was directed by admirals and generals in war rooms, but fought by indoctrinated foot soldiers who were prepared to lay down their lives. Living veterans, now numbering a mere 792 – a stark drop from 1.4 million in the 1980s – continue to bear profound scars.

Mr Hideo Shimizu, 95, a former member of the notorious Unit 731, made headlines in China when he visited a memorial in the north-eastern city of Harbin in August 2024 and bowed in apology.

He recounted feeling powerless to go against his superiors’ orders, having been assigned to what was the Imperial Japanese Army’s biological warfare unit, and remains haunted by nightmares from witnessing human specimens.

Tokyo’s official position has been to acknowledge Unit 731’s existence, but it refuses to confirm or deny human experiments, citing a lack of conclusive documentation. In March, Mr Ishiba told Parliament: “The means to verify facts have been lost with history.”

Mr Shimizu, who broke his silence in 2015, continues to share his experiences publicly but suffers from slander and abuse from Japanese right-wing commentators online, who deride him as a “senile old man”.

He told the Asahi Shimbun newspaper: “If you say 100 times something did not happen, it becomes as if it really never did. That is more frightening.”

Japan’s discomfort with its history as a colonial power and wartime aggressor – coupled with a political shift to the right – is evident from how the subject is discussed in the country’s history textbooks.

Mr Ishiba recounted an anecdote to a forum in May of a meeting with Singapore’s former prime minister Lee Kuan Yew at his home in the 2000s, when he attended the Shangri-La Dialogue in Singapore as defence minister.

“Mr Lee asked me, ‘Do you know what Japan did in Singapore during WWII?’,” Mr Ishiba said. “I replied with the knowledge I learnt in history class at school. Mr Lee looked sad and said, ‘Is that all you know?’. I felt so ashamed that I began reading various books to learn about what had actually happened during the war.”

His anecdote epitomises how the same historical events can be interpreted differently, with opposing versions sometimes written off as “revisionism”.

The divergence is stark even at home, when comparing Yushukan Museum within the grounds of Yasukuni Shrine in Tokyo – which enshrines 2.5 million war dead, and is highly controversial for the 14 Class A war criminals in their midst – to the peace museums in Nagasaki or Okinawa.

Despite Japan having previously made war apologies and reparations in accordance with international law, and a consistent refusal to be drawn into “apology diplomacy”, the country’s hawkish shift has unnerved neighbouring countries. The likes of China, North Korea and South Korea believe that Tokyo has not adequately atoned for incidents like the Nanjing Massacre or its exploitation of wartime labour and “comfort women”, and the war is still an open, festering wound that can be weaponised for nationalist purposes.

Yet as Japan stands at the crossroads, what is undeniable is that the country has come to be relied upon by the US, as well as regions in Europe and South-east Asia, as a stalwart defender of the existing rules-based international order in the Indo-Pacific, particularly to counter a more assertive China.

But Shizuoka University historian M.G. Sheftall, an American who has lived in Japan for 40 years, said: “Geostrategic realities of the 21st century aside, one factor behind this collective memory shift is the natural process of transgenerational historical amnesia.”

He noted a “wilful political and ideological effort” behind the amnesia, and added: “What has been salient is the long, slow decline of once canonical and sacrosanct Japanese postwar pacifism, to a point where opinions that were absolutely unutterable in public 20 years ago are now openly expressed.”

Still, Mr Tatsukuma Ueno, 97, a former pilot of the Imperial Japanese Army’s 66th Squadron, vows to keep talking about the war as long as he is able to.

Peace comes at a premium and cannot be taken for granted, he told a news conference in July, adding: “As a Japanese citizen, I am really happy to see that Japan has become what it is today. People have grown accustomed to peace.

“This is totally different from the environment in which I was brought up, and I think the fact that there is no war and peace prevails is the best thing one can have.”