Japan's Kurumi Nara claimed local bragging rights with a stunning 6-3, 6-0 win over rising star Naomi Osaka on Wednesday to reach the second round of the Japan Women's Open.

Nara, ranked 108th in the world, romped past the 46th-ranked Osaka in 70 minutes to book a meeting with China's Wang Qiang, who won her opener 7-5, 6-2 against Taiwan's Hsieh Su-wei on Monday.

"It was an all-Japan battle and I know what a tough opponent Naomi is, but I think I did what I had to do in today's match," said Nara, who lost her only previous meeting with Osaka on the tour in Birmingham, England, last year.

"She is a fantastic player and I took the approach of playing as a challenger today and I think that led to me winning."

"Naomi is a power hitter and I expected her to play shots with pace and instead of trying to match that I had to slow it down and get into rallies. I think I was able to do that."

Nara, whose only WTA Tour victory so far came at the 2014 Rio Open, conceded only three points en route to taking a 4-0 lead in the first set under blazing sunshine on the outdoor hardcourts at Ariake Tennis Forest Park.

Although sixth seed Osaka, who shocked defending champion Angelique Kerber at the U.S. Open last month, pulled it back to 4-3, Nara held serve and broke her 19-year-old opponent for a third time, taking the set with a crunching forehand.

Nara started the second set just as she had the first and after racing into a 5-0 lead, the 25-year-old secured victory when Osaka sent a forehand long.

"I don't really think I played at all," said Osaka. "I just think emotionally I wasn't really there." 

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"I originally thought I was going to have a lot of fun and just play well. But when I started the match I was really nervous and felt a lot of pressure and I guess I didn't really cope with that well."

In other first-round matches, three-time champion and fifth seed Samantha Stosur was knocked out, the Australian going down 3-6, 7-5, 6-1 to Spain's Sara Sorribes Tormo, but defending champion Christina McHale of the United States advanced thanks to a 6-2, 6-4 win against Montenegrin Danka Kovinic.

Second seed Zhang Shuai of China progressed after beating Richel Hogenkamp of the Netherlands 6-3, 6-3 and Kazakhstan's Zarina Diyas came from behind to oust Japan's Misaki Doi 3-6, 6-1, 6-1.

"After taking the first set I started to make a lot of mistakes," said Doi. "I got a bit nervous and am disappointed that I wasn't able to play well."

In the big shock of the first round, top-seeded Frenchwoman Kristina Mladenovic crashed to a 6-4, 6-3 defeat to Croatian qualifier Jana Fett.

In second-round matches, Japan's Miyu Kato pulled off a huge 7-5, 6-3 upset win over fourth-seeded Czech Kristyna Pliskova, third-seeded Belgian Elise Mertens topped Poland's Magda Linette 6-1, 7-5 and Serbian Aleksandra Krunic overpowered American Alison Riske 6-3, 6-4.