The Japanese have traditionally sat on tatami (a padded straw mat) at their homes.The proper way of sitting on tatami is called seiza. It is to bend the knees 180 degrees tuck your calves under your thighs and sit on your heels. It is considered polite to sit seiza style on formal occasions.
Another way of sitting is cross-legged (agura). It is a more relaxing way to sit. Starting with legs out straight and folding them in like triangles. This posture is usually for men. Women would usually go from the formal to an informal sitting posture by shifting their feet just off to the side (yokozuwari).
BowingBowing in Japan is a way of saying "hello" , "goodbye" , "thank you" and even "I'm sorry" . The dept of the bow and duration of the head is kept lowered is depending on the age of the person ,status of the person involved and relationship to on another.
Here is a video to show the correct way to bow in japan :)