Higa, one of 13 Japanese players in the field, did not have a blemish in her six-birdie performance, a record low round on debut at the championship.
It earned her a one-shot lead over German qualifier Esther Henseleit and a two-stroke cushion over Celine Boutier of France with half the field back in the clubhouse.
Higa did not have high expectations after some mediocre recent form on her home tour, but a co-operative putter is a great way to turn things around.
"I felt really great through 18 holes," said the 25-year-old from Tokyo. "Putting was the best thing."
Higa and her fiance Ikioi Shota are a celebrity couple in Japan, where Shota is a successful professional sumo wrestler.
"He just said to me: 'Have fun and enjoy yourself'," Higa said of the advice he had offered.
Big things have been expected of Higa since she twice won the Japan amateur championship before turning pro in 2012.
She has accrued five Japan LPGA Tour victories, and last year made her mark on the international stage by finishing equal fourth at the Women's British Open.
Second-placed Henseleit barely got into this week's field after losing a playoff at a sectional qualifier in England, which left her as the first alternate.
She had a reprieve when some withdrawals opened up a spot.
"I was very sad when I missed out but about a week-and-a-half ago I found out I had got in," said the 20-year-old.
While Higa and Henseleit had no trouble coping with demanding greens and a testing morning breeze, some of the pre-championship favourites were slow out of the starting gate.
World number one Ko Jin-young bogeyed four of her first 10 holes en route to a one-over 72, the same score as defending champion Ariya Jutanugarn, who birdied her final two holes.
(Reporting by Andrew Both; Editing by Ken Ferris)
