The Czech entered the event as the top seed, but she fell at the last hurdle, losing 6-1 4-6 6-1 to Nara in a humid 32°C environment.
"I have an asthma problem so I couldn't breathe," Zakopalova told reporters. "But it's not an excuse. Well done to Kurumi. She deserved it. She played really well."
Zakopalova has now lost six consecutive singles finals.