It has been several years since the 29-year-old played sevens rugby competitively.
Before meeting up with the team in Japan, Radradra participated in the Super Sevens Series that was held in the UK.
According to the Bristol Post, Radradra played for the Official Wooden Spoon Marauders Sevens team where they won the plate final.
Fiji has two matches on the opening day of the 7s competition.
They will face Japan on 26 July at 12pm (local time) before taking on Canada at 8pm.
Fiji will then play Great Britain on the next day.