Victory looked unlikely after a poor first half by Brad Thorn’s men, with the Sunwolves running in three tries to one to hold a 16-point lead at the break.
Liam Wright’s try after a 20-metre drive from a maul was all the Reds had to show as Jamie Booth, Rahboni Vasayco and Dan Pryor all scored for the Sunwolves.
Needing to score first after the break, the Reds did just that Paenga-Amosa and Hoopert scoring to reduce the margin to two before Paenga-Amosa’s second put the Reds ahead for the first time in the 66th minute.
From the kick-off however the Reds handed the initiative back to the Japanese team, with rookie five-eighth Isaac Lucas colliding with winger Chris Feauai-Sautia and knocking the ball on.
The Sunwolves made the most of the error to hit the front with substitute halfback Keisuke Uchida scoring before a Hayden Parker penalty extended the margin to five.
Rather than dwell on allowing the Sunwolves back in the Reds finished with a wet sail with McDermott’s 76th minute try and Stewart’s penalty sealing a vital win.
Queensland face the Brumbies in Brisbane next Sunday while the Sunwolves host the Lions next Saturday.