Lupin walks into a job that's supposed to be simple, steal a fake gemstone, get paid, move on. Within minutes the job implodes into something nobody expected: a murder, an immortality riddle, and a woman who might actually be alive forever. This is Lupin at his best, where the con is never what it looks like and the real score is always hiding three layers deeper than the surface game.
A legendary gemstone surfaces on the black market, and Lupin the 3rd receives an unwelcome summons from the underworld's most dangerous crime boss. She forces him to steal the Mermaid's Scale, a prize worth killing for. But when Lupin examines his haul, he realizes the truth: what he grabbed was a fake, and the genuine article holds something far more valuable than money. The real Mermaid's Scale is a key to immortality itself, hidden somewhere within an ancient mystery no one has ever solved. Before Lupin can process this discovery, his coercer turns up dead. Her seemingly ageless companion Misa becomes the target of a ruthless arms dealer determined to claim the secret of eternal life for himself. Suddenly Lupin isn't just hunting treasure: he's racing against an opponent who wants to weaponize human immortality and reshape the world through endless conflict. With his crew scattered across danger and time running out, Lupin must stay one step ahead of everyone who wants the scale, including those willing to kill for the power to never die.