Someone who likes Japanese things more than their equivalents, Just because they are Japanese.
This term originated from the meme depicting a picture of a random place, with the face next to it being unhappy, and the same place under it having the word Japan over it, with the face next to it being very happy.
Not to be place place Japan, butãææãæ ã«æãããsounds way cooler than "I think therefore I am".