Cooper has been relegated to third-string flyhalf behind ageing aces Matt Giteau and Freddie Michalak at Toulon where he is playing fullback in the run to the Top 14 play-offs.
Toulon owner Mourad Boudjellal would love Goromaru's package and cult status at his club for next season which would be another knock to Cooper's viability.
Cooper's two-year deal at Toulon includes an option clause to exit after one season.
The formative approach the Reds have made to him could well firm into a return at flyhalf next season to the patch where his rugby has thrived most in a 107-game career.
Goromaru's selection to start tomorrow is huge because it is the dream match-up that the tour groups jetting in from Tokyo and the local Japanese community are crazy for.
Karmichael Hunt needs more time to fix a groin niggle.
Match-winning centre Samu Kerevi (hand) has not been named but has been given until the 3.05pm kick-off on Saturday to show he is fit to start as a late change for Campbell Magnay.
"I'm going to be doing the best for my teammates at the Reds and also enjoying playing my teammates from the World Cup so it will be exciting," Goromaru said through a translator.
Added Reds co-coach Matt O'Connor: "I expect him to play significantly better now he's got last weekend's 80 minutes of footy behind him because he hasn't played a lot."
Japanese rugby's most recognisable face is enjoying his "Aussie Goro" persona. He chatted in thongs and gave Brisbane's Japanese restaurants "10-out-of-10."
He had an admirable take on his limited playing minutes.
"The mark of a player is to play the cards he's given and for me it is making the most of the time I get," Goromaru said.
The Sunwolves' often-porous defence has given up 52 tries in 10 games which means Goromaru and the Reds could have open spaces to shine if they do the hard work first.
Equally, Japanese flyer Akihito Yamada has scored a competition-high eight tries as the talisman for the Sunwolves' bold attacking game.
