While Japan and China enjoy ever closer relations, their respective communist parties remain, ironically, at loggerheads. An icy climate of name-calling has existed since a divorce in 1966 created by China's Cultural Revolution. And, once united in their assessment of the world situation, the two communist parties now find themselves on opposite sides of many key issues.
So, although the Chinese recently have made reconciliatory overtures, the Japanese communist Party (JCP) leadership remains suspiciously cautious.
One key signal from Peking was a remark by Communist Party Chairman Hu Yaobang at a Central Committee meeting in June admitting past mistakes and denying any Chinese intention of interfering in the domestic affairs of foreign communist parties.
Attacks on the present JCP leadership as "revisionist" have also ceased.
But from a Japanese point of view, reconciliation is not that easy: The past simply cannot be dismissed in a few vague sentences.
As a precondition for talks, for example, the JCP seeks a formal apology from China for past interference in its affairs.
Kenji Miyamoto, party chairman, recently said that Chairman Mao Tse-tung's attempts to claim leadership of the international communist movement was his most serious error.
And an official party statement said that the recent reassessment of he Cultural Revolution by the Chinese partyhs Central Committee was "inadequate" in that it dealt only with the domestic impact and ignored the effects the period had on foreign communist parties.
Informed sources said one reason for Mr. Miyamoto's caution is his feeling that the present Peking leadership is still in a transitional period and that its current pragmatic policies may not be sustained.
The Chinese and Japanese comrades were once the closest of brothers in arms.
When the late JCP Chairman Kyuichi Tokuda and othe top leaders were purged by US occupation authorities in 1950 for organizing strikes, they sought haven in China.
The two parties maintained a staunch common front against "American imperialism." When the Sino-Soviet dispute flared up in the early 1960s, the JCP sided with China.
When the US and Soviet Union concluded a treaty banning atmospheric nuclear tests, which the Chinese opposed, the present JCP leadership went so far as to expel pro-Soviet members who supported the treaty.
But the Cultural Revolution spoiled everything. On a 1966 visit to Peking, Mr. Miyamoto criticized Mao's disruptive bid to revitalize the original national revolutionary spirit. And he also rejected Chinese demands that the JCP foment armed revolution at home, according to the Japanese party's version.
China's sudden turnabout over the US in the 1970s further aggravated the dispute.
Thus, in its unrelenting battle against Soviet imperialism, Peking now supports the once-condemned Japan-US security treaty, while the JCP remains in stubborn opposition.
China also supports a militarily strong Japan now, again in direct opposition to the JCP policy line of unarmed neutrality.
Thus, there are many barriers to normalization of relations even though many analysts consider the original cause of quarrel has been removed by the Chinese admission of past mistakes.
But Hiroshi Tachiki director of the JCP's international division says: "any talk of reconciliation is premature, and I can't predict when any movement might occur."
One consolation for the Chinese: the JCP 's relations with Moscow are just as bad.