The reality that there isn't a whole lot to do airside. Even hitting all of the stores can be done in an hour or so. Nothing to do in the lounge except watch the planes, eat, take a shower, and grab a nap. If you allow time for heading into town with 9 hours you can get 5+ hours exploring part of Tokyo. The Edo-koji shopping is landside but really doesn't open until around 10ish. Tokyo Station is about 30 minutes from the airport, Akihabara is about 40, and Shinjuku is about the same. Ueno is about 40 minutes by train depending on what you want to see/do. Only issue is dealing with the rush hour crowds on the train.