AC does code share to many asian cities that are not served by its own metal, however the list is fairly limited. I wonder what the reasons are. Is it due to AC not wanting to have more codeshares, or does Canada not have the bilateral agreements in place with many countries to allow such codeshares? Maybe the large number of *A carriers in Europe compared to Asia has something to do with it, as well as the number of flights/cities AC flies to Europe to feed the codeshare flights (remember that to book the codeshare flight a passenger will have to be connecting to/from an AC flight).

According to AC's timetable, AC serves the following asian cities (I'm limiting the cities listed to east asia):

Bangkok, Thailand
Busan, Korea
Fukuoka, Japan
Hanoi, Vietnam
Hiroshima, Japan
Ho Chi Minh City, Vietnam
Matsuyama, Japan
Miyazaki, Japan
Nagoya, Japan
Okinawa, Japan
Osaka, Japan
Phuket, Thailand
Sapporo, Japan
Singapore, Singapore
Takamatsu, Japan