Unfortunately, with their warped sense of geography only by calling US.

For the Circle Asia fare *A uses the following breakdown:
South East Asia: Singapore, Malaysia, Indonesia, Thailand, Brunei, Philippines, Vietnam, Cambodia, Myanmar, Laos.
North Asia: Hong Kong, Japan, Korea, Taiwan, China.
South West Pacific: New Zealand, Australia.

Source: http://www.staralliance.com/en/trave...asia_fare.html


Historically the following definitions were used to describe geographic areas:
North Asia China, South Korea, Taiwan and Guam
Japan
South Asia Bangladesh, Borneo, Brunei, Cambodia, Hong Kong, Indonesia, Laos, Malaysia, Myanmar, the Philippines, Singapore, Sri Lanka, Thailand and Vietnam
Central Asia India, Nepal and Pakistan

My guess is that they probably moved Japan into the North Asia and then lumped everything else together :-(