Mamo, a very old, and extremely rich man calling himself “God” is searching for the secret to eternal life. The secret may lie within the Philosopher Stone (or as the Americans call it: The Sorcerer's Stone). Which he gets Fujiko to manipulating Lupin into stealing. And in exchange she, aswell as Lupin, will be granted eternal life in this new world. But immortality is a curse, not a gift. And Lupin has no interest in living forever. After all he does what he does for the thrill. If there were no risks what would be the motivation. And if Fujiko thinks that she’d be free and spend herlife with Lupin in this new world she’s wrong. Because Mamo will need a queen by his side. And the beautiful Fujiko would make a great trophy.

Despite it taking a while to actually get to the main plot the movie is paced pretty well. There is actual build up. The title “The Secret of Mamo “ is a better overall title for the movie than “Lupin vs The Human Clone“

The villain looks ridiculous but is genuinely interesting.
The movie has a great atmosphere to it. And some great aesthetics and visuals. An anime form the late 70s that aged like fine wine.

This movie is longer than your typical Lupin special. At a length of 1H42.
Its also the first Lupin movie. Effort really went into it.

A plot very similar to this gets used in a story arc in Lupin the 3rd Part 4 Italian Game (2015). Where Leonardo da Vinci is cloned in modern times and wants to create a world with only the humans he sees as worthy enough.