Calling someone an otaku in Japan would be a very bad insult . However , in America , otaku is often used to refer to fans of anime and manga .
Common uses are anime otaku ( a fan of anime ) , cosplay otaku and manga otaku ( a fan of Japanese graphic novels , anime being the animated version of , that is so popular among today 's Western cultures ) , pasokon otaku ( personal computer geeks ) , gÄ `` mu otaku ( playing video games ) , and wota ( pronounced ` ota ' , previously referred to as `` idol otaku '' ) that are extreme fans of idols , heavily promoted singing girls ( diva .