Duhan van der Merwe was also on the scoresheet in a 57-17 victory.
Fiji paid the price for a sluggish start and ill-discipline as they fell to a record defeat to Scotland at Scottish Gas Murrayfield in their opening match of the Autumn Nations Series.
Shorn of the majority of their Rugby World Cup 2023 stars, Fiji have named a starting XV exclusively drawn from Super Rugby outfit Fijian Drua.
Fiji head coach Mick Byrne has named four uncapped players in his 39-man squad, which also features a host of overseas stars for their Autumn Nations Series campaign.
Grand final time in Osaka saw the bright lights come on and the stars shine as Japan and Fiji clashed in a heated contest to decide the 2024 Pacific Nations Cup champions.
Fiji head coach Mick Byrne liked what he saw in his side's Pacific Nations Cup semi-final win over the USA and so has backed largely the same cast of players to get the job done in Saturday's final in Osaka.
Fiji player ratings: The Flying Fijians brought their trademark flair to this contest, with the USA struggling to contain the free-running Fijian backs.
The Flying Fijians have made three changes from the team that dismissed Tonga in round three of the Pacific Nations Cup as they look to claim another title in the revamped tournament.
Fiji have recorded a statement 42-16 win over rivals Samoa to start their Pacific Nations Cup campaign under coach Mick Byrne.