Ahhh, Nakano.... It's been three years since I was last there. Sadly I too, like Haruto, realized the shallowness of my otaku-ness on the third floor the first time I went. The main building is connected to a big video game arcade, btw, so if you go there in a group and you're finished ahead of everyone else, just try your luck with the UFO catchers or go upstairs and try out a pod game. If you stay late enough, the izakayas just outside are great places to eat.