Well geographically Japan is in north -east Asia. I guess is normal not to consider them self western. Nevertheless is also where EU place this country. according to this standard they establish economical and political cooperation. Other north-east Asian countries are China, Hong Kong, Taiwan, South/north Korea . Japan is part only of ASEM (Asia-Europe meeting) so I guess is here they place themself. All other regional agreement don't include Japan so they must consider themself an north -east Asian country.