Tension between Japan and its Asian neighbours escalated on Wednesday, the 67th anniversary of the end of World War Two, as South Korea and China both told Tokyo to do much more to resolve lingering bitterness over its past military aggression.
Despite close economic ties in one of the world's wealthiest regions, memories of Japan's wartime occupation of much of China and colonisation of South Korea run deep in the two countries.
But South Korea prompted an official protest from Japan after comments by President Lee Myung-bak which some saw as going too far by insulting Japanese Emperor Akihito.
Adding to the tension and underscoring how history haunts Tokyo's ties with Beijing and Seoul, two Japanese cabinet ministers paid homage at a controversial Tokyo shrine for war dead.
The rows in part reflect scepticism over the sincerity of Japan's apologies for wartime and colonial excesses.
Feuds over rival claims to rocky islands have also heated up, a sign of how the region has failed to resolve differences over its past nearly seven decades after its defeat and the end of the occupation and colonisation of its neighbours.
On Tuesday, South Korea's Lee told a group of teachers that Akihito should apologise sincerely if he wants to visit South Korea, saying a repeat of his 1990 expression of "deepest regrets" would not suffice.
Japan's Foreign Ministry said it had lodged a protest with Seoul over the remarks about Akihito, who has spend much of the past two decades trying to heal the wounds of a war waged across Asia in his father's name.
Lee, whose visit on Friday to an island claimed by both Seoul and Tokyo frayed ties between the two US allies, called Japan an "important partner that we should work with to open the future".
But in remarks commemorating Korea's liberation from Japan's 1910-1945 rule, he also said the countries' tangled history was "hampering the common march toward a better tomorrow".
He urged Tokyo to do more to resolve a dispute over compensation for Korean women abducted to serve as sex slaves for wartime Japanese soldiers, known by the euphemism "comfort women" in Japan and long a source of friction.
"It was a breach of women's rights committed during wartime as well as a violation of universal human rights and historic justice. We urge the Japanese Government to take responsible measures in this regard," Lee said.
Japan says the matter was closed under a 1965 treaty establishing diplomatic ties. In 1993, Tokyo issued a statement in the name of its then-chief cabinet secretary and two years later set up a fund to make payments to the women, but South Korea say those moves were not official and so not enough.
Speaking at a ceremony marking the war's end on Wednesday, Prime Minister Yoshihiko Noda acknowledged the "enormous damage and suffering" caused by Japan to other countries, especially in Asia.
"We deeply reflect upon (that) and express our deepest condolences to the victims and their families," he said, vowing that Japan would never go to war again.
Tapping into anti-Japanese sentiment remains a way to seek public support in South Korea and China, which face leadership changes in coming months. And some experts see a new strain of nationalism is surfacing in Japan amid gloom about the future.
In a sign of the domestic pressures in Japan, National Public Safety Commission Chairman Jin Matsubara and Transport Minister Yuichiro Hata visited the Yasukuni shrine for war dead, defying Noda's urgings to stay away.
Many see the shrine as a symbol of Japan's past militarism because 14 Japanese wartime leaders convicted as war criminals by an Allied tribunal are honoured there with Japan's war dead.
Wednesday's visits were the first by cabinet ministers since the Democrats swept to power in 2009, promising to forge warmer ties with the rest of Asia. Pilgrimages by then-Premier Junichiro Koizumi to Yasukuni during his 2001-2006 term in office fuelled anger in both China and South Korea.
Chinese Foreign Ministry spokesman Qin Gang said Japan should reflect upon why such visits upset the rest of Asia.
"The essence of the Yasukuni Shrine issue is whether or not Japan can properly recognize and deal with its past history of militarism and invasion, and whether or not it can respect the feelings of its Asian victims, including those in China," Qin said in a statement.
The Japanese ministers' defiance was another sign of Noda's weak grip on his fractious party, which has recently suffered defections over his signature plan to raise the sales tax.
Japan's ties with South Korea, where resentment over its colonisation of the peninsula remains strong, took a sharp turn for the worse after Lee visited an island - known as Dokdo in Korea and Takeshima in Japan and near potential seabed gas deposits - claimed by both countries last Friday.
Relations with China, where memories of Japan's occupation of large parts of the country in the 1930s and 1940s still rankle, have also been strained by renewed bickering over uninhabited islands in the East China Sea that are near potentially huge oil and gas resources.
On Wednesday, a ship carrying activists from Hong Kong, China and Macau seeking to stake China's claim to the islands entered nearby waters, and an activist on board said by satellite phone that Japan's Coast Guard had fired water canons after the vessel ignored warnings not to approach.