Japanese emperor Akihito has for the first time expressed “deep remorse” over Japan’s role in World War Two.
He was speaking at a ceremony to mark 70 years since his country surrendered.
Prime Minister Shinzo Abe said the Japanese service personnel who died had “sacrificed their futures”, but on Friday he was accused of failing to properly atone for Japan’s actions.
A service was also held at the US naval base of Pearl Harbor, where the conflict began in the Pacific.
More than 2,000 people were killed in the surprise Japanese attack in 1941, which drew the US into the war.
Members of the US Navy and dignitaries from the US and Japan laid wreaths and unveiled a new plaque at the scene.
At the memorial service in Tokyo on Saturday, Mr Abe and Emperor Akihito observed a minute’s silence.
Emperor Akihito struck a more apologetic tone than Mr Abe, with an expression of remorse for the nation’s wartime aggression.
“I attend this memorial ceremony with a deep and renewed sense of sorrow… I earnestly hope that the ravages of war will never be repeated,” he added.
The prime minister said the country would “always reflect the past and hate the horror of the war”.
But in a statement on Friday he stopped short of issuing a fresh apology to the victims of Japanese aggression, angering South Korea and China.
He said that future generations should not be “predestined to apologise” for their country’s wartime actions.