If you need to wash your cloths during your stay in Japan, the best way is to reserve a hotel which has a coin laundry in it. The machine usually costs 100~200yen for washing and another 100yen for 30 min of drying. The difference from North American washing machine is that you cannot specify the temperature, but the good news is that it is a cold water wash, and so is appropriate for all your delicate and colored clothing. Regarding the detergent soap, usually there is a vending machine in the laundry room, which you can buy for 100yen or so. If there doesn't appear to be any soap, take a close look at the washing machine. Some will even have a jug of soap attached that will automatically mix soap into the wash for you. Also, there are usually pants presses that will help smooth out your pants, and these can be used free whether or not you wash your clothes.