Electronic train passes in Tokyo, similar to London's Oyster cards, are being fitted with technology that tracks pupils' movements and sends the results to their parents.
The Pasmo, originally released as a contactless payment pass for Tokyo trains, has been gradually adding other services to its card.
The latest allows parents to choose a card that registers when their offspring enters the home, and registers arrival at school. Each time a checkpoint is passed, a message is sent to the parent's mobile.
In Japan, one of the safest countries in the world, some children already carry GPS-enabled mobiles so Mum and Dad know exactly where junior is, while others have trackers stitched into their clothes.