Notification device, notification system, notification method, and recording medium

A notification method comprising:

• by a computer,
• acquiring read information when a reading device reads first product identification information on a product, the first product identification information being stored in a price label tag that is detachable and attached to the product held by a customer, and second product identification information on the product, the second product identification information being stored in a spare tag that is not detachable from the product;
• determining whether the first product identification information is readable based on the read information;
• and
• notifying determination when the first product identification information is determined to fail to be read.

A non-transitory recording medium storing a program that causes a computer to perform the steps of:

• acquiring read information when a reading device reads first product identification information on a product, the first product identification information being stored in a price label tag that is detachable and attached to the product held by a customer, and second product identification information on the product, the second product identification information being stored in a spare tag that is not detachable from the product;
• determining whether the first product identification information is readable based on the read information;
• and
• notifying determination when the first product identification information is determined to fail to be read, the non-transitory recording medium being readable by the computer.