Lupin III: Twilight Gemini no Himitsu

The intrepid Lupin is given a huge diamond called Twilight by Don Dorune, the chief of a shady crime syndicate in Europe.

The diamond is actually the key to opening treasures left by the Gelt tribe a century ago.

Lupin heads to Morocco, the reported location of the treasure.

But there are two Twilights, and without the two keys, the door to the treasures is certain not to open.

The other key is said to be possessed by Don Dorune's child, but there is no way of knowing who or where the child is.

At the same time, a bunch of ruthless assassins hired by those who proclaim themselves the Gelt tribe's descendants are also looking for the treasures.

A huge fight over the treasure erupts, and Lupin is naturally right at the centre of it.