Mazinger Z: Mycenae no Densetsu no Maki

Mazinger Z: Mycenae no Densetsu no Maki (マジンガーZ ミケーネの伝説の巻 Majingā Zetto mikēne no densetsu no maki) is a prequel manga to the original series by Go Nagai given away with the first produced models of the special edition 40th Anniversary DX Soul of Chogokin Mazinger Z models. It shows the origins of the Mazinger Z and the influence of its creation. Due to its limited numbers, the booklets are considered valuable by collectors, even more so than the models they were released with.

Summary
After finishing the completion of Mazinger Z, Juzo Kabuto reminisces about how he first found Mazinger's predecessor on Bardos Island, where he and his son Kenzo Kabuto fled the fall of the island with two modified Ghost Mechanical Beasts called Majin Z1 and Great G1 but are ambushed by Dr. Hell. The two successfully fend off Dr. Hell's mechanical beasts but Kenzo is left crippled after the battle, and flee with their two mecha by stealing Dr. Hell's floating research lab.

5 years later, Kenzo Kabuto has heavily modified Hell's floating lab into the Science Fortress Laboratory and the two separately reformatted Mazin Z1 and Great G1 into Mazinger Z and Great Mazinger respectively. As he is about to hand over Mazinger to Koji Kabuto, he is attacked by Baron Ashura and in his dying breath reveals Mazinger to Koji pleading to use it to stop Dr. Hell's Machiavellian schemes. Donning his helmet, Koji starts up Mazinger Z, and the battle for Earth begins...

Characters

 * Juzo Kabuto: the main character of the manga, having researched the ancient but advanced machines of the Mycenae Empire, he created Mazinger Z for his grandson Koji to use.
 * Kenzo Kabuto: Juzo's son and Koji's father; in this iteration, Kenzo was part of his father and Dr. Hell's expedition to Bardos.
 * Koji Kabuto: Juzo's eldest grandson and the inheritor of Mazinger Z.
 * Dr. Hell: Juzo's arch rival and former colleague. Having discovered the Mechanical Beasts on Bardos, he strives for world domination.
 * Mycenae Empire: An ancient but technologically advanced empire that built giant robots.
 * Ghost Mechanical Beast Majin Z1: A Ghost Mechanical Beast used by the Mycenae Empire; served as the model for the Mazinger Z.
 * Ghost Mechanical Beast Great G1: Another Ghost Mechanical Beast used by the empire; served as the model for the Great Mazinger.

Trivia

 * Mycenae no Densetsu no Maki wasn't the first instance in which a booklet bundled with a piece of merchandise ended up becoming a rarity. A similar situation occurred with the initial 1992 release of Cap Toys' Stretch Armstrong.