I'm targeting some SE Asia areas and pulling some Amazon posts in with WP Robot. My choices are amazon.com or amazon.jp. Which would you choose? I'm leaning toward .com since english is more universal, but really don't have any experience. I assume someone who reads chinese can't read japanese necessarily.
You need to consider also whether the products you are promoting (on Amazon .jp or .com) will ship to the target areas. I imagine very few products will ship from Amazon.com to SE Asia, but I might be wrong.
Amazon is not that popular in SE Asia regions. You may want to join some other affiliate program that's popular in SE Asia.
You might also want to check where the majority of your traffic is coming from. And there's no need promoting .jp when your Japanese audience won't understand half of what's on your site.