The memo, uncovered and reported by the Nihon Keizai Shimbun on Thursday, rocked the nation's political circles because it indicated that the Emperor, posthumously known as Showa, stopped paying visits to Yasukuni Shrine because it enshrined Class-A war criminals in 1978.

The revelation that Emperor Hirohito's had antipathy against the war criminals is a severe blow to conservative politicians and academics who have defended them.

They have argued that the military tribunal, controlled by the Allies, ignored the colonial advancement by the Western powers and one-sidedly identified Japan as the only evil state that waged wars to conquer Asian countries.

Those conservatives put much faith in the prewar sense of nationalism, which was based on the Emperor system. Yasukuni has also long been an ideological foothold for such nationalism.

Shiro Akazawa, a professor of Japanese politics at Ritsumeikan University and an expert on Yasukuni issues, said the Emperor's comment in the memo is particularly troublesome for the shrine because, in the prewar era, Yasukuni enshrined those who dedicated their lives to the state only after the Emperor approved the list of candidates for enshrinement.

For Yasukuni at that time, the Emperor was considered tantamount to the state itself.

In the postwar era, even though the Constitution stipulates a strict separation between state and religion, the practice still exists and a list of those to be enshrined is submitted to the Emperor in advance, although officially he does not have the right to approve or disapprove any of the names.

"When we brought a list (including the war criminals) to the Imperial Household Agency, an official at the agency clearly said that (the Emperor) won't visit anymore if (Yasukuni) enshrines people like them," recalled Baba.

As Baba indicated, Emperor Hirohito, who had visited the shrine regularly to pray for people who died for the state, no longer visited the politically controversial site after 1975.

Emperor Akihito, who succeeded Emperor Hirohito after his father's death in 1989, has not visited the shrine since his enthronement.

Yet Akazawa pointed out that repeated protests by China and South Korea appear to be pushing many Japanese people toward supporting the prime minister's visits to Yasukuni.