Japan Women's Open second seed Veronika Kudermetova set the tone for Monday's WTA Tour action with a straight-sets win over Varvara Lepchenko.
All the seeds competing across the tournament in Hiroshima and at the JiangXi Open in Nanchang, China, were triumphant.
Kudermetova did it the hard way, though, her 6-4 6-2 victory coming after she had fallen 3-0 behind in the first set.
She was joined in round two by fellow seeded players Alison Van Uytvanck and Zarina Diyas, while Priscilla Hon also progressed.
In Nanchang, third seed Magda Linette beat Giuliana Olmos 6-3 6-2, fifth seed Rebecca Peterson saw off Xun Fang Ying 6-0 6-3, sixth seed Viktorija Golubic downed Jaqueline Cristian 6-3 6-2, and seventh seed Kateryna Kozlova thrashed Greta Arn 6-2 6-1.