Grudge! The longest Day of the Kurogane House (Middle Part)
Energer Z appeared with Kenzo Kabuto as pilot. Pygman who appears in an hologram implies that Energer Z is looking for Zeus arm, the source of photon energy. Tsubasa appears and gets rid of Pygman's hologram and eventually his idea of handing over Zeus arm to Energer Z. Kouji activates Mazinger Z and fights off Energer Z. The two exchanges blows and fire power. Mazinger Z in the end was losing the battle and Baron Ashura convinces Tsubasa to reveal the whereabouts of Zeus arm in order to help Kouji. Memory came back to the sick Tsubasa when they have discovered Zeus arm as the source of photon energy. The same photon energy Juzo and Kenzo used to built Energer Z with Tetsuya Tsurugi as pilot. Dr. Hell revealed his true plans of world domination.
Aired 15/08/2009EP 20 - Grudge! The longest Day of the Kurogane House (Middle Part)

Mazinger Edition Z: The Impact!
Set in the near future, humanity enters another energy revolution following the discovery of Photon Power. Derived from the ore discovered under the foothills of Mt. Fuji, its intended use was to solve the world's energy problems with its unimaginable power. Seeking this energy is Dr. Hell, a madman craving world domination who with his subordinates Baron Ashura, Count Brocken and Viscount Pygman, commands an army of mechanical beasts excavated from the ruins of ancient Greece to seize the Photon Power Lab for himself. Meeting the attack head on is the hot-blooded teenager Kabuto Kouji, who pilots the Photon Powered robot built by his grandfather, Mazinger Z. But in this battle between Dr. Hell and the Kabuto family, many legends surrounding the Mycenaean Civilization and Bardos Island, as well as the secrets of Mazinger Z remain shrouded in mystery.
A new series based on the mecha show that started it all, Mazinger Z. Shin Mazinger Shougeki! Z-Hen starts over from the beginning with a new cast, to tell a new story unrelated to the original show.
(Source: shin-mazinger.com)