Following a tip from Fujiko, Lupin and Jigen dive into the sea floor of Kiritappu to uncover a lost underwater treasure said to contain the secrets of time travel. After evading a confrontation with the authorities, the gang is suddenly transported hundreds of years into the past by a mysterious man who introduces himself as Kyousuke Mamoh. With Lupin, his companions, and the relentless Inspector Zenigata now trapped in a bygone era, they must navigate two feuding tribes and solve the puzzle of the hidden treasure before Mamoh can erase Fujiko from history by wiping out her ancestor.