J.a.N are usually dark skin men who have an irrational obsession with Japan. They are extreme versions of Otakus. An otaku will be obsessed but have good taste in Japanese cultural products. While a J.a.N will eat up anything a Japanese person shits out their ass and calls 'art'. It's one thing to listen to some underground Japanese metal bands such as 'Corrupted' but to listen to shitty J-pop is criminal.
They have an inability to separate the tasteful from the awful. To them anything Japanese is good. The sort of movies, music or animation they would avoid in america is automatically good if it's Japanese(anime). They would never watch a shitty Nickelodeon cartoon or Disney show about little preteen girls but will obsessively follow a ShMjo anime about 10 year old flat chested Japanese girls getting their first period and digging in the garbage dump to collect items the boy they have a stalker-crush on throws away. They will find this fascinating and say it's better than Death Note/Code Geass/Balls Rider and even Angelic Layer.
A: 'Why are you being such a Jap-a-Nigga?'
B: 'Respect my Mind man, you got any hentai? I need some shit with some girl putting the worms in another girl's ass and then shitting it out. That's real hot.'
A: 'Dude you're a fucking disgusting Jap-a-Nigga!'
B: 'You a hater homie. Acting scaze son'.'