Recently the Yomiuri News reported the following:
About the "Body Scanner" that could see through the clothes of air travellers, and to detect suspicious things that a metal detector could not discover, the Ministry of Land, Infrastructure and Transport announced on the 8th that the guideline on Airlines safety was changed so that scanners might be taken as one of the means for security inspection to be carried out in a domestic airports, and each airline may introduce this inspecting device by the end of this month.
According the announcement, the Ministry of Land, Infrastructure and Transport carried out the proving tests on five models of the body scanners in New Tokyo International Airport from July to September. As a result, it was evaluated that when the "Millimeter wave" , being one kind of the electro-magnetic radiation was radiated directly at the passenger, the body line was clearly projected, and it was confirmed that it had an equal sensing capability as "Contact Inspection" that the inspecting personnel could feel. In future, it would be up to individual airlines to decide whether to introduce it.
For security purpose, the installation of body scanners at the airport is understandable.