The Japan women's national team, ranked 12th in the world, fell 20-10 to No. 13 South Africa on Saturday in the second of their two tests.
Japan's Ayasa Otsuka scored the first try minutes after kickoff, but two tries by Ayanda Malinga put the visitors ahead for good at Saitama Prefecture's Kumagaya Rugby Stadium near Tokyo.
Seina Saito crossed the whitewash after the final hooter to lend some credibility to the score line. She scored twice a week earlier in Japan's 15-6 win.
Japan will play seventh-ranked Ireland on Aug. 20 and 27 in their buildup for the World Cup in New Zealand, starting in October.