5 June 1974
Due to South Africa’s Apartheid regime in the 1970s and 1980s, many countries were cautious to be seen as allies with the country. Japan was one of these countries. Japan depended heavily on trade and it could not risk receiving negative international attention. On 5 June 1974, the Japanese government announced that South Africans would no longer be granted visas to enter Japan. The announcement meant that they were not to take part in sporting, cultural and educational activities. The ban came into effect on 15 June 1974.
References

Payne R.J. Japan’s South Africa Policy: Political Rhetoric and Economic Realities from Jstor [online] Available at: www.jstor.org [Accessed on 25 June 2012]|Mukonoweshuro E.G. Japanese commercial interest in South Africa from T and F online Available at: www.tandfonline.com [Accessed on 25 May 2012]