AFTER almost five decades, Japan officially has accepted that many of the Korean, Chinese, and other Asian women who served the Japanese military as prostitutes during World War II were forced into that role. The admission, and the accompanying apology, are progress. But they fail completely to compensate for what the outgoing government calls ''injuries to the mind and body that cannot be healed''. It is only a year since Japan first recognised the involvement of the Imperial Army in recruiting ''comfort women''. But the insulting official line remained that the estimated 200,000 women who worked in military brothels were there voluntarily. This week's apology was overdue and doubly justified. It is remarkable that North and South Korea should have accepted the apology so readily as sufficient reason to drop the subject from their diplomatic exchanges with Japan. There has yet to be a full investigation of the women's ill-treatment or reparations to the survivors. Japan should not content itself with the LDP's muttered, death-bed confession. By taking this step on the way out of office, the LDP cynically has made the handling of the issue even harder for the in-coming administration. The new eight-party coalition has said it will seek reconciliation with its Asian neighbours by recognising Japan's war guilt and offering apologies to those who suffered from Japanese brutality. Now it is left with the domestically more difficult gesture of conducting an enquiry and paying compensation. If the new government is genuine about seeking to put its relations with the rest of Asia on firmer footing, there is much left for it to apologise for. The Rape of Nanjing, in which an estimated 300,000 Chinese died; the medical experiments on prisonersin Northern China and the brutality of Japanese rule elsewhere in Asia still rankle. Despite Emperor Akihito's admission that Japan has inflicted great sufferings on the people of China, outright apology and some genuine gesture of contrition are still awaited.