The Final Do-or-Die Battle!! Send Tetsuya and Koji to Hell!!

"The Final Do-or-Die Battle!! Send Tetsuya and Koji to Hell!!" it's the 55th episode of Great Mazinger. This episode first aired in Japan on September 21, 1975.

Summary
Tetsuya and Koji are having flight training. After Great Mazinger almost collides with Mazinger Z, Koji questions why Tetsuya pulled such a dangerous maneuver. He answers that, without real risk, their training won't be effective. Tetsuya continues harrasing Koji until Mazinger Z falls in to the ocean.

Inside the Science Fortress Laboratory the entire team holds a meeting to discuss their strategy. Koji wants to change their approach. Instead of just shooting down whatever the Mycenae Empire throws at them, he wants to find their base and destroy it so they all can go back to a normal life. On the other hand, Tetsuya argues that a search for the enemy base may cause the Myceneans to lash out and increase casualities. As the argument seems to be intensifying, Jun intervenes.

After Tetsuya asks Kenzo's opinion, Jun reasons he and Koji will accept whatever his decision turns out to be. Dr. Kabuto says he understands both points of view, but maybe they should reconsider they strategy so far. Although Kenzo claims he will discuss the subject further with Dr.Yumi, his desire to change their tactics suggests he choose to favor Koji's suggestion.

The Science Fortress's radars pick up a signal. There's a Warrior Beast approaching.

Mazinger Z and Great Mazinger quickly find Gold Phoenix. Koji asks Tetsuya to follow their plan and not destroy it so they may follow Phoenix back to its hideout. Tetsuya ignores his pleas and finishes Gold Pheonix off with Great's Breast Burn.



Jun confronts Tetsuya when he returns to the fortress. She berates him for acting so petty. After Tetsuya claims that he, unlike Koji, doesn't have any real connecting to Kenzo, Jun slaps him. Tetsuya goes on to say he can't stand the way Koji acts like a spoiled boy getting favors from his father and claims all their efforts will be for nothing if they keep pandering to him. He finishes the rant by warning Jun that she will also be left out when Sayaka Yumi returns.

Unbeknownst to them, Kenzo was listening their conversation from the beginning.

Aboard Demonika, the Great Marshall of Hell gives his men a mission briefing. With Gold Phoenix, he was able to perceive conflict between Tetsuya and Koji. Hell wants to use this opportunity to launch an all out attack to conquer Earth.

Koji, who went back to the Photon Power Lab to store Mazinger Z, realizes he is being surround by Catloos and Mycenaes. Shiro asks Tetsuya to go help him. Kenzo tries summoning Tetsuya to the control tower, but he ignores both of them. Great Mammoth arrives in time to stop Koji from docking.

Tetsuya finally shows up at the control tower. Shiro and Kenzo tell him even though they aren't blood related, he still part of their family. As Tetsuya's taking too long to come to a decision, Jun sorties alone.

Boss and his gang are aboard Boss Borot going to see Sayaka who just arrived from America. They find her on her way to the Science Fortress Laboratory, but before they can stop to talk with her, Jun tells them Koji is in trouble and asks for Borot's help. With both of them keeping Great Mammoth busy, Koji is able to activate Mazinger Z.Tetsuya decides to help Koji. However, as soon as he leaves the base, he's ambushed by Vulcania. The Warrior Beast shows up with the sun behind its back blinding Tetsuya for enough time to allow it to hit Great Mazinger with its missiles. The attack pierce through Brain Condor's canopy and wounds one of Tetsuya's arms.

Meanwhile, Demonika attacks the Science Fortress Laboratory. Dr. Yumi denies Sayaka's request to be allowed to deploy as he argues Diana A isn't powerful enough to make a difference against Warrior Beasts that are able to give so much trouble to Great.

After Great Mazinger destroys Vulcania, the resulting explosion knocks Tetsuya out. The Great Marshall of Hell immediatly changes Demonika's course. As the Mazinger Team realizes he's going to try to finish Tetsuya off, Kenzo orders the Great Boosterto be launched.

Recurring

 * Tetsuya Tsurugi
 * Jun Hono
 * Koji Kabuto
 * Shiro Kabuto
 * Kenzo Kabuto
 * Great Marshall of Hell
 * Boss
 * Nuke
 * Mucha

Machines

 * Great Mazinger
 * Venus A
 * Mazinger Z
 * Brain Condor
 * Hover Pilder
 * Queen Star
 * Gold Phoenix
 * Vulcania
 * Great Mammoth

Weapons

 * Great Mazinger
 * Drill Pressure Punch
 * Breast Burn
 * Thunder Break
 * Venus A
 * Koushiryoku Beam
 * Mazinger Z
 * Southern Cross Knives
 * Iron Cutter

Trivia

 * In the Latin Spanish Dub, when confronted by Jun about his behaviour towards Koji, Tetsuya mentions Koji's popularity with women 'including Jun' as one of the reasons for not liking him. The line is jarring not only for being absent from the original version, but also because Jun is both the only woman in the Science Fortress Laboratory as well as the only character who gives more attention to Tetsuya than Koji after the latter returns from America.
 * The subplot concerning the search for the Mycenean main base is left unresolved. The series ends with its whereabouts remaining unknown.
 * General Birdler's absence suggests he did die at the end of Great Mazinger Episode 47, A Silver Bullet!! The Super Speed Great Booster!!.