Bartoli eased by Melinda Czink 6-2, 6-2 behind a service game in which she lost 16 points over eight games. She dropped just five points in her four second-set service games.
She also won half the points when receiving in the set and finished with five service breaks.
No. 7-seeded Chanelle Scheepers and Eleni Daniilidou advanced with similar 6-2, 6-2 scores. Scheepers won two-thirds of the points while defeating Alla Kudryavtseva. Daniilidou won 62 percent of the points when receiving and had six breaks in eight games in beating Anastasia Pivovarova.
Tamarine Tanasugarn opened her Japan Women's Open title defense with a 6-3, 7-5 win over No. 8-seeded Christina McHale.
Also Monday, Misaki Doi topped Coco Vandeweghe 6-4, 6-4 and Mathilde Johansson ousted Irina Falconi 6-3, 6-2.
Falconi, McHale and Vandeweghe were three of the five Americans in the draw in Osaka. The others -- Jill Craybas and Vania King -- meet in a first-round match Tuesday.