On our fourth day in Tokyo (Saturday, June 9), we were finally able to sleep in a bit and hit the 7-11 for our eggs and onigiri at 8:30am instead of the usual 6am.  By 10, we were inside the National Museum of Nature and Science in Ueno Park.  The children loved the dinosaurs, aviation, and car exhibits, as did I. Just before noon was an experience we scheduled for our son, who started taking karate a few months ago, but it was probably my favorite activity we…