It continued their domination of softball, adding to their under-18 and senior WBSC World Cup titles.

The US won all nine of their matches at the tournaments bar a 2-1 defeat to hosts Japan, earning them a place in the final against Puerto Rico, who had won seven and lost one going into the decider at the Ota Stadium.

The opening round contest between the sides had finished 6-0 to the US, and they again started strongly with runs in the first inning from Aspen Boulware and Stevie South.

Efficient pitching from America's Macie Bryant allowed just one hit for Puerto Rico, but it took until the sixth inning for Samantha Alekman to get home for the US to add to their lead and seal a 3-0 victory.

Boulware was later named the tournament's most valuable player, contributing four home runs and six runs batted in.

She described the success as an important step on the road to Los Angeles 2028, where softball along with men's baseball is set for its Olympic return having missed out on Paris 2024.

"This is a step towards LA28, with softball being played in the Olympics," Boulware said.

"Being number one in the world is awesome and I am so honoured to be part of it."

Japan earned the bronze medal with a 2-0 victory against Chinese Taipei.