The Australian claimed victory with an 82kg snatch and a clean and jerk of 97kg, amounting to a winning score of 179kg.
After coming second to Toua in the clean and jerk, Yamasaki dominated the match.
Charlotte Moss (NZ) took silver and Marry Kini Lifu (SI) claimed the bronze medal.
With the standard being set high for the Port Moresby 2015 Pacific Games weightlifting competition, host PNG will have to step up to the challenge to add to its medal tally.
Source: Pacific Games Media