Let's start off with something rather blaise, but necessary--laundry.
If you're lucky you will at least have a mini washing machine in you apartment. Mini in that it can wash about 1/2 the amount of an American washer so you will be forced to wash laundry4-5 times a week.
Even the smallest dryers will cost you a minimum of 300 US dollars or 3o,000 yen, so unless you both have the room and plan on staying at least 2 years, it's not worth it. Every single apartment I've ever seen has a small balcony or patio or something that allows you to hang your clothes out doors.
Bike Grease STAIN REMOVAL: As 99% of the foreigners here will be forced to only have their bikes for local transportation, you will at some point get bike grease on your clothes. This happened recently and after searching the web (my stain book didn't cover that type of clothing disaster.), I found a rather curious "cure" and it WORKS!!
--> Let that one piece of clothing run through the whole washing cycle by itself, but instead of using any stain remover or detergent, add a can of COKE. After it goes through one whole wash and rinse cycle, you can wash it normally with other clothes. ^.^
I used this trick on my favorite light beige pair of pants and they came out perfectly.
I couldn't believe it.
WARNING FOR WOMEN: Do NOT hang your underwear outdoors! Japanese men have a weird fetish about women's underwear (hence the used underwear vending machines in the seedier areas of metropolitan cities), and it may be stolen. If you have to hang it outside, make sure you only do it while you are at home. This applies to people living on the uppen floors, too. There's nothing more exotic than a foreign women's underwear (apparently).