In order to save their family workshop from foreclosure, a young inventor suggests to his brainless older brother that Lupin may be the answer to their financial problem. They build a smart safe for the Greater Tokyo Bank which can only opened by someone with no brainpower, as a special challenge to Lupin, the world's smartest thief. Vexed by the resilience of this obstacle, Jigen, Fujiko and Goemon begin to implement a sadistic regime of sleep deprivation, beating and exercise to kill off Lupin's brain cells...