I'm an anime fan because I love the story lines, and character designs. I'm also a fan because I dedicate some of my time to helping administer a little known Anime website, you might have heard about it (Here's a hint, you're posting on it).A fan, aficionado, or supporter is someone who has an intense, occasionally overwhelming liking and enthusiasm for a sporting club, person (usually a celebrity), group of persons, company, product, activity, work of art, idea, or trend. Fans of a particular thing or person constitute its fanbase or fandom. They often show their enthusiasm by starting a fan club, holding fan conventions, creating fanzines, writing fan mail, or promoting the object of their interest and attention.
Because of that, I have spent thousands of dollars on anime/manga, and I've even traveled hundreds of kilometers for anime (Going from where I live to Calgary takes about 2 and half hours, each way).
The contents of your room, or whats on your wall doesn't make you a fan, those are just byproducts.