Great Britain's bid to reach the Fed Cup World Group for the first time in 25 years started with defeat as Heather Watson lost to Japan's Naomi Osaka.
Osaka, ranked 22nd in the world and one of the form players on the WTA Tour this year, won 6-2 6-3.
British number one Johanna Konta will aim to level the tie against Kurumi Nara in Saturday's second singles.
The best-of-five tie concludes with a doubles rubber and the reverse singles from 04:00 BST on Sunday.
If Britain win in Miki, near Kobe, they will be promoted to World Group II - the first time they would have a place among the top 16 teams in the competition since 1993.