On the fifth floor of an otherwise unassuming electronics shop on a side street in Akihabara hides a store dedicated exclusively to robots. You can get everything from fully built (and very expensive) robots to DIY model kits to parts to build your own robot from scratch. It's a robotics geek's paradise, tucked away, like so many things here, way up in a nondescript building and hard to find. I would advise against investing in that giant Hello Kitty robot, though. Not only is it Hello Kitty, which is a few strikes against it, but it doesn't do anything other than respond to you when you say things into it's microphone, including "I love you" in Japanese when you curse at it in English. Artificial intelligence my ass.