(even if you aren't vegan)
Chooms' Patented Method of Japanophile Eradication
SO you have a Japanophile on your hands. Don't fret, you can turn them into honest Americans yet! Japan is not inherently better than America, and the best method is to simply demonstrate how great America is, using uniquely American experiences. American.
Contents
STEP 1. CULTURE JAMMING
YOUR friend refuses to consume anything but Japan. Whenever they have to do sequential art, they ask the teacher if they can make it right-to-left. They listen to J-Pop and J-Rock, which really is empirically terrible. So, the solution here is to shove America down their throats, but not too much. Don't be arrogant about it, and don't choose the most "AMERICA HECK YEAH" media you can, because that causes reinforcement of how great Japan is in their minds. However, whatever you do, do not give them British stuff, for you don't want an Anglophile.
Reading Material
Since your friend clearly refuses to read anything but magna (the only form of Japanese literature), you might think it is appropriate to give them comic books. This is wrong, because it's not different enough. They will identify the plots to superhero comics as "inferior" to their beloved Japan, and even if they don't, now you've got a magna AND comic-book consumer.
Instead, attack the magnas (not openly) on terms they'll "Get". Give them better stories than magna. I recommend novels that are simultaneously entertaining enough to catch their attention, but at the same time of worth. Whenever they look away from their books or whatever, switch it out for one of these books. Hide the magna far away, throw it if you have to.
Television
Japan has mediocre comedies, because Japan has a really underdeveloped sense of humor that relies on extreme slapstick. It is acceptable to give them Three Stooges, unlike the comic book example above, however it probably won't capture them. I would recommend showing them 30 Rock and It's Always Sunny in Philadelphia whenever they try to watch comedies.
Dramas are a different matter entirely. However, you want to keep your shows in the realm of "Only in America". Mad Men is a good choice, but V isn't.
And if they want action shows, god help us all.
Movies
Movies need to be tailored specifically to what the watchers like in their Anime films. The cinematography? Citizen Kane. The deep look into a character's psyche? Patton. Philosophy? Man, who watches Anime for the philosophy? Comedy? Any given Bill Murray movie (Start them off with Lost in Translation then move on to his other films.) Basically do this with everything.
Music
Steal their iPods and all their Japanese stuff, and if you can delete the stuff off their harddrive. Replace their JRock or JPop with stuff that's not Country or anything. No, go with the most American of all genres: Rock and Roll. Yes, the British revolutionized it, but it's still ours. Load them down with alternative and pop and refuse them any opportunities to listen to Japanese things.
STEP 2: MAINTAIN, MAINTAIN, MAINTAIN
THIS might take a long time, but keep up the strategies listed above and you'll havee a Yankee Doodle Dandy on your hands. By the end of college. If they don't resist. Which they probably will.