The Lupin gang is once again dragged onto a wild treasure hunt! This time, the objective is a mysterious, small dragon statue that even Goemon's steel-rendering blade Zantetsuken cannot cut. The artifact, which once eluded even Lupin the Third's esteemed grandfather, rests deep undersea inside the infamous Titanic, and is the key to unlocking the mystery of Zantetsuken's almighty strength. A wealthy gangster, Lupin, and Goemon all want the statue for themselves!

The 31st year of the Showa Era (1956) marked the tenth year since Japan's defeat in World War II. It was when Japan took its first step out of post-war poverty to rejoin the international community. In old downtown Tokyo, a teacher and her students try to pass down Doyo (Japanese traditional children's songs) as the root of Japanese cultural identity to the future generations.

When Fujiko secures a file that documents the location of the fabled Columbus Egg – a mystical relic that controls the weather – she quickly recruits Lupin and the gang to track down the long-lost treasure. Unfortunately, her memory of Lupin and his friends are wiped out almost entirely. Can the gang restore Fujiko’s memory before the Egg falls into the hands of a madman?