One second before Mazinger's explosion!!

Synopsis

Grand Duke Gorgon's Mechanical Beast, Grieks ΨII, attacks the Photon Power Laboratory as if to avenge Baron Ashura. Sayaka tries to call Koji, who had gone hiking, but he dismisses it as another of her usual fits and won't listen. Dr. Morimori sets out to fetch him instead, only to be caught in a trap that blows up his car and takes his life. Koji boards Mazinger Z and, wielding the Iron Cutter that Dr. Morimori left behind, unleashes a furious all-out attack on Grieks ΨII.