The translation for otaku is just nerd. That really isn't an insult. Actually being a nerd is considered good. I mean I'm one of the few people who still play Yugioh and when I showed my cards to everyone they all kinda accepted it and thought it was awesome.
English
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It doesn't really translate to "nerd". It better translates to someone with obsessive interests. Be it anime or baseball. And in Japan it isn't good to be see an an "otaku" anything, mainly because of the stereotypical anime obsessive types.
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There is nothing wrong with loving anime. Having something you are passionate about is always good.
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But being an otaku doesn't mean you have passion. It means you have an obsession that wanders into the realm of being creepy.