I was busy contemplating the Tokyo subway map trying to figure out how to get to a good toy store, when the building started swaying back and forth, lamps shaking. I instantly knew it was an earthquake, and a strong one... It was a good minute or so. I looked it up, but couldn't find it right away, but just now it was posted on USGS. About 200 miles north of where I am. 6.9 magnitude.