The world number 18 and favourite for women's singles gold in Nagoya thrashed Thailand's Patcharin Cheapchandej 6-1, 6-0.
It was a mismatch, with Patcharin ranked 517th in the world, and top seed Eala will face Taiwan's UK-born eighth seed Joanna Garland in the quarter-finals.
Eala, 21, last month became the first player from the Philippines to win a WTA Tour title.
She has become wildly popular in the Philippines, her every match followed by large numbers of cheering fans.
Eala is skipping the prestigious China Open in Beijing to represent her country at the Asian Games.
She had a bye in the first round.