At Fujiko's warning, Lupin and Jigen embark on a mission to excavate the ocean floor in Kiritappu, in search of a mythical submerged treasure, rumored to unlock the secrets of time travel. With the authorities hot on their trail, they encounter an enigmatic figure, Kyousuke Mamoh, who transports the Lupin gang back in time by centuries. In this ancient era, Lupin, Inspector Zenigata, and their comrades must navigate the battles between feuding factions and unravel the enigma of the lost riches before Mamoh alters the course of history, putting Fujiko's ancestry in jeopardy and endangering her very existence.