System

A system comprising:

• a first relay device provided on a first network hierarchy level;
• and
• a second relay device provided on a second network hierarchy level higher than the first network hierarchy level, wherein
• the first relay device includes
• a first information reception unit that receives target object information about a target object, the target object information being transmitted by a radio tag attached to the target object in accordance with a predetermined timing;
• a first information storage unit that stores the target object information received by the first information reception unit;
• a first change determination unit that determines whether there has been a change in a status of the target object, based on a status of reception of the target object information by the first information reception unit;
• and
• a first information transmission unit that transmits the target object information about the target object to the second relay device, when the first change determination unit determines that there has been the change in the status of the target object.