Hannu is a Green Lantern from the planet Ovacron Six. Warriors there believe that using a weapon is something to be looked down on, and for this reason, Hannu would rather use his own strength than rely on his ring in battle. When Hal Jordan became Parallax, Hannu was one of the "Lost Lanterns" that was left for dead in space.
Years later, Jordan and Guy Gardner traveled to the Manhunters' planet Biot to rescue the Lost Lanterns believed to be dead. There they found the Lanterns strung up to be drained as living power batteries for the Manhunters latest model of giant and massively powerful robots. The Manhunters were now working under the rule of their Grandmaster, Hank Henshaw, the Cyborg Superman. During Hal and Guy's battle with their robotic enemies, Hal freed Ke'Haan, who in turn freed his fellow prisoners. Hannu awoke and immediately tore into the Manhunters, preferring to rely on his brute strength to tear the android apart. Hannu and his fellow Lanterns escaped Biot moments before the mechanical planet was destroyed.
