The Flying Metal Arm, Dyan

"The Flying Metal Arm, Dyan" it's the tenth episode of Mazinger Z. This episode first aired in Japan on February 4, 1973.

Summary
After Koji leaves to discuss Dyan N4's recent attack, Baron Ashura and his Iron Mask break into Koji's house to kidnap Shiro.

At the Photon Power Lab, Koji deduces that their enemy must have some sort of aquatic base. He asks Sayaka to come investigate the seaside region with him later. When Boss asks about it, Sayaka teases him by saying she's going on a date with Koji.

Back at his house, Koji finds Baron Ashura waiting for him. He demands to be given Mazinger Z in exchange for Shiro's life and leaves.

Later, Koji meets with Sayaka, Boss and his gang next to a lighthouse. Sayaka shows him that there's a construction happening at Araiwa Island. Turns out, Ashura is building a front line base. After Koji tells them about Shiro, they see Saluud moving away from Araiwa Island. Koji tries to attack it with the Hover Pilder, but Ashura threats to kill Shiro if he doesn't stop.

That night, back at Koji's house, the gang discuss what to do. Sayaka offers go to save Shiro in Koji's place so Baron Ashura doesn't kill him. She asks Boss to hire a boat so they can go together investigate the island.

The next day, Baron Ashura sends out Dyan N4 to steal more material for the construction. In its way out, the Mechanical Beasts spots Sayaka, Boss, Nuke and Mucha approaching the island on a boat. Sayaka manages to use the radio to call for help before Dyan N4 destroys the boat, but the gang escapes unharmed.

Koji arrives with the Hover Pilder and drops lifeboat to his friends. He flies to the island to rescue Shiro. After Baron Ashura learns about this, he decides to put Dyan N4 inside Saluud and sneaks off to attack the Photon Power Lab.

At the beach, Koji's friends spot Saluud approaching. Sayaka gets in her bike and rushes back to warn her father about the Mechanical Beast then sorties in Aphrodite A to fight Dyan N4.

Back to the island, Koji launchs a second lifeboat to break Shiro's fall before using the Photon Gun to shoot the rope holding his brother. After saving Shiro and killing the Iron Mask who was watching over him, Koji flies back to help Sayaka.

Aphrodite A gets defeated, but Sayaka is saved by Mazinger Z who manages to destroy Dyan N4.

Recurring

 * Koji Kabuto
 * Sayaka Yumi
 * Shiro Kabuto
 * Gennosuke Yumi
 * Dr. Hell
 * Baron Ashura
 * Boss
 * Nuke
 * Mucha

Machines

 * Mazinger Z
 * Hover Pilder
 * Dyan N4
 * Aphrodite A

Weapons

 * Oppai Missile
 * Finger Missile (Debut)
 * Photon Gun (Debut)

Trivia

 * Despise being seasick, Boss is shown to be a faster swimmer than Sayaka, Nuke and Mucha. This contradicts later episodes The Ocean Tomb Of Mazinger Z and Great Mazinger's Endure, Shiro!! Heroes Don't Get Days Off in which Boss is show to be completely unable to swim unaided.
 * After the rescue, Koji seems to forget his brother back at the enemy base. Shiro isn't with him as he leaves Araiwa Island with the Hover Pilder nor does he appears again in this episode.