I am a sucker for Japan and their culture, but actually living there I'm sure would be a cultural shock, no matter how much you may expect to be familiarized with any of it.
Having a friend to tag a long who speaks the language would give you a head-start in both developing a grasp of the language, culture as well as the surroundings, but I'm fairly certain considering how welcoming they are, it wouldn't be too too difficult to do either way.
That said, I've never been, but it's at the top of my bucket list in terms of travel destinations, but yes, I'd also be fairly willing to even live there based on what I've seen and learned over the years.