 Although the story depicted in the film is fictitious, the crime  actually took place on December 10, 1968. The amount stolen in a  single crime is still the highest record in Japan (equivalent to  todays $2M), and despite more than 100 evidences left behind, with  170,000 policemen against 110,000 suspects spending almost a billion  yen in the investigation, nobody was arrested and the stolen money  was never found. The investigation was officially closed for  prescription in 1975.