In the afternoon of January 26, 1948, a man claiming to be a health official went to a branch of Teikoku Ginko (Imperial Bank) in the Tokyo district of Shiinamachi and told all 16 present that dysentery had broken out in the neighborhood.
After handing the bankers a business card identifying him as an epidemiologist, the man told all those present to drink a few drops of liquid which he claimed was a cure. However, the liquid was actually poisonous.
Twelve of the 16 people died, and the man escaped with cash and checks worth 160,000 Yen.
The Teigin incident, as the crime became known, was one of the most sensational mass murders in Japan after the war. A painter named Sadamichi Hirasawa was subsequently tried, found guilty and sentenced to death for the crime.
Hirasawa was arrested because the police uncovered evidence relating to the exchange of business cards with personal data. There were two other very similar cases of attempted theft from banks using poison in the months before the robbery. In both cases, a single man left a business card at the crime scene.
In one of the two incidents, the perpetrator used a card marked “Shigeru Matsui” from the Ministry of Health. The original owner of the card had an alibi for the afternoon of 26 January 1948 and told police that Hirasawa was among those to whom he had given his card.
Many secrets remain about the incident, including what kind of poison was used and whether Hirasawa was wrongly convicted of the crime.
However, the incident also shows how impressive a business card with a size of about 5½ cm x 9 cm can be in Japan. Business cards open doors and in extreme cases also safes.