The Japanese do some strange things, at least from the viewpoint of this particular foreigner. In the U.S. you’d never open someone’s front door and walk in without being invited, but it’s quite common in Japan for someone to open the door and walk into the genkan (the low foyer area where you leave your shoes) and ask in a loud voice if anyone is home — no one thinks anything of it, since that part of the house is officially considered part of the outside. (In old Japanese farmhouses during the Edo Period, this area was much larger, and farm animals were kept there during the winter.) In the U.S. there are certain subjects you avoid out of politeness, such as religion, why a married couple doesn’t have kids, or how much an expensive car or home cost. In Japan, however, some of these topics seem quite neutral and might come up during small talk. The Japanese also think nothing of bringing up a person’s weight gain as a part of casual conversation, which you never do in the U.S. I can’t count the number of times I’ve met business associates in Tokyo and had the conversation start out with, Peter-san, sukoshi futotta? (“Peter, have you put on some weight recently?”). Sheesh.
The shoe area (genkan) in a Japanese house is considered ‘outside’ the home.