I found this article on Yoshiaki Yoshimi that might be of interest. It goes into more detail of who he is and how he became involved in the comfort women issue. In regards to the issue over the lack of official documents, he says, "The fact is, if you can't use anything except official documents, history itself is impossible to elucidate." According to Yoshimi and other historians, the emphasis on official documents is part of the government's strategy to control wartime history.
There was another article that was critical on China's policy of "airbrushing" its own history, saying that it was no different from Japan. "Young Chinese tend to know next to nothing about their country's own conquests, or even about atrocities committed in living memory by their own government. What they are taught is what Japan's nationalists seek to teach: their own essential goodness."
So in the end, is Japan and China no different in how they are trying to portray/shape its past history? Including Korea, these three countries, like any other country, have an agenda in how they want their national history portrayed and what should be emphasized. As we saw last week, Korea has its own problems with an education system that teaches hatred towards the Japanese (I'm generalizing here). And I'm sure there are other issues that are being airbrushed or contained by the Korean government. So how can "historical correctness" be done when everyones version of the truth is different and the government has a stake in portraying a certain type of history?