In-form Chie Arimura put together a bogey-free 66 Friday to take the lead after the first round of the NEC Karuizawa 72, while Ai Miyazato matched par in her first event in Japan since capturing her maiden LPGA title at last month's Evian Masters.
Arimura, whose runnerup finish at last week's AXA Ladies came on the back of her second win of the season at the Stanley Ladies, rolled down six birdies at Karuizawa 72 Golf North Course to establish a one-shot advantage over South Korea's Jeon Mi Jeong.
Arimura just missed out on back-to-back titles in Japan last Sunday after she was eliminated in a playoff at the AXA event won by U.S. LPGA player Momoko Ueda.
Jeon also enjoyed a blemish-free round and was followed in third place by Shinobu Moromizato and Hiroko Fukushima.
Yuko Mitsuka and Rui Kitada were among a quartet tied another shot back. Ueda shot a 70 and Miyazato had two birdies and as many bogeys in her round of 72.
Money rankings leader Sakura Yokomine went 1-over, Mika Miyazato, no relation to Ai, struggled to a 74 in her first domestic tournament since turning pro and Erina Hara made a sluggish start in her defense of the NEC title with a 75.