Success has proved hard to find this summer for Han, who arrived in Nanchang with only one win in her past five tournaments. And it looked like more disappointment was on the cards when Namigata raced through the opening set.
However, Han had other ideas, pinching a tight second set to ensure a tense finale. She continued to sail close to the wind in the decider, coming within a couple of points of defeat before eventually prevailing, 2-6, 6-4, 7-5.
"I've been trying to get used to the weather," Han said. "I didn't feel in good form in the very beginning and was just trying to hang in there at the end. It wasn't my best tennis today but I won and now I can look forward to the next round."
There she will face compatriot Duan Ying-Ying, who eased past Marina Melnikova, 6-2, 6-2. Also advancing was Risa Ozaki, who wisely kept her time on court to a minimum, swatting aside lucky loser Han Na-Lae, 6-3, 6-1. The No.7 seed's reward is a meeting with Nicha Lertpitaksinchai, after she defeated fellow Thai qualifier Peangtarn Plipuech, 6-2, 6-4.