When registering your Arai helmet you will be asked for the Serial Number and the Approval Number of the helmet - this is also a way for you to check your Arai is genuine.
Both the Serial Number and Approval Number are located on the white label on the helmet's chin strap (the label may be orange on some older helmet models):
The top number beginning with "P" is the Approval Number and the bottom number (in this instance "0007712") is the Serial Number.