A man shows the tiny QR code stuck to his nail in Iruma, Japan. /CFP Photo

The free service provides tiny waterproof QR code stickers to elderly people at risk of wandering away from their homes and getting lost. Launched in December, it is a first in Japan. /CFP Photo

The technology allows police to get people's details such as their address, telephone number and identity number, simply by scanning the 1 square cm stickers. /CFP Photo