A non-Asian person who is obsessed with Asian pop music, art, fashion, etc. etc. etc. Will typically learn snippets of Japanese in order to seem more legit and dye their hair.
"Why did Jessica dye her hair black, and why is she greeting me with 'moshi moshi?'"
"Yeah, she's an Asian Fan."
"Konnichiwa, Olivia-chan!"
"God, Amanda, stop being such an Asian Fan."