The 24-year-old winger always had it in his mind to return to the 15-man game which he played as a youngster in Fiji and decided the time was right when the Queensland Reds came knocking with a substantial offer.
Vunivalu reportedly signed a deal in late November worth $1.8 million with the Reds and Rugby Australia.
While he didn't comment on the size of the deal, he said hamstring issues, which ruled him out of the Storm's painful preliminary final loss to Canberra last year as well as the World Cup Nines, helped him make the decision.