When visiting a Japanese family, its best to bring a small gifts like a box of cookie, or cake or some kind of fruits. 

• At the front door, when about to enter say aloud "ojama shimasu". 
• When entering, put on the room slippers that is prepared at the door entrance. 
• After putting on the room slippers, bend down and arrange your shoes neatly...position your shoes as toes facing the front door. 
• Wait for Japanese host to tell you the seating position...maybe in living room, maybe in tatami room. 
• When serve with food/drinks, start eating/drinking by saying aloud to the host "itadakimasu" with a slight head nod. 
• When food/drinks is finished and about to leave say aloud to the host "gochiso sama deshita" with a slight head nod. 
• Arrange your room slippers neatly at entrance and slip into own shoes. 
• When leaving the host family, say aloud "ojama shimashita" with a smile to the host and a slight bow. 
• If desire to give the children in the family some cash gifts, make sure the cash is in an envelope and covered.

• At the entrance of toilet, take off room slippers and put on the toilet slippers that is prepared at door entrance. 
• Enter toilet with toilet slipper on.  Do not wet the floor with water.  Always flush after using toilet. 
• Some houses have waterlet attached to the toilet...just push button of waterlet while seated and push stop button when finish. 
• When leaving toilet...make sure the toilet slippers is position as toes facing toilet in front of toilet door.  Then put on the same room slippers again.

AT THE FOOD SUPERMARKET.

• If buying more than 1 item, always take the food basket laid out at the entrance of the shop. 
• Do not press and poke at fruits/food. 
• When paying at cashier, put the cash in the money plate prepared near the cashier...do not give cash on the cashier's hand. 
• When receiving receipt and change...smile at cashier and say "domo" with a small head nod. 
• Return back basket and trolley to the same position when taking. 
• Always check cash change while in front of cashier and always keep receipt, even if buying only one item.....confused with all the adat???   Sorry, in Japan...do as the Japanese do :)