Due to a general, nation-wide, lack of insulation and central heating winter is often very cold inside your house/apartment, school and of course, outside. So, finding out how to keep warm is a mission we all undertake around November/December. Warm clothing can be found in most department stores, Jusco, and Uniqlo.

How to keep warm
  • Small electric heaters - really good for heating your feet
  • Kerosene heaters (make sure there is ventilation for fumes to escape, and to air out your place every couple of hours or so)
  • Air conditioners with a 'warm' function
  • Try heating smaller areas (1 room)
  • Thermal under layers
  • Draft proofing your house, and covering big windows with bubble wrap or other insulation
  • For floors, padding (often silver mat stuff that helps to insulate your floors)
  • Small heat packs (ホッカイロ - hokkairo) to carry or put in shoes
  • 'Kotatsu' - low table covered by a duvet/'futon' with a heater underneath.
  • Purchase hot drinks from vending machines or stores. Use them like hand warmers/heat packs. Also drink them.
  • Thick, heavy blankets. Fleece blankets can also generally be bought for cheap and are quite warm.
  • Electric blankets - put them under your sheets and turn on a couple minutes before you scramble from your kotatsu to your bed. Then, like magic, your bed is warm.
  • Portable stoves and nabe cooking - instead of leaving your heated kotatsu cave and trying to cook in a cold kitchen, bring the cooking utensils to you and cook up some nabemono. The hot stove will warm you up along with the food.

Winter dress code
  • Work: Long sleeves, ties (for men), full length trousers or skirts with thick tights. (generally, it is not okay to wear jackets/coats inside the staff room or class room, but find out by asking or watching other teachers) Generally, thick sweaters are allowed in "warm biz" as are vests.
  • Many layers of clothing (so you can easily take them on and off; outside/staff rooms/class rooms can be cold. Inside shops/stores can be hot).
  • Multiple socks, or really thick thermal/wool socks.
  • Hats/scarves/neck warmers
  • Thermal under trousers/shirts
  • Coats and gloves
  • Warm boots or shoes for walking to school in, and warm indoor shoes/slippers.
  • Occasionally, waterproof coats and trousers.

Winter-proofing your house
Check out this excellent guide on SurvivingInJapan:Winter tips
Also, the guide on heaters is very informative: Heater tips

Frozen pipes
Pipes freezing is a common occurrence in Japan during winter. You can try to prevent this by insulating pipes. Often, pipes freeze overnight when the temperatures plummet below 0 degrees celcius.
Generally, temperatures in Okayama are often mild enough that by the afternoon the pipes will not be frozen. So, waiting until the water comes back on as the weather warms slightly during the day is the best option.
This may not be too much of an inconvenience, and you can plan ahead, and bathe/shower in the evenings instead of the mornings.

Your house is likely to have big, single-pane windows which will make your rooms feel so much colder.
Covering them with some type of insulation can make a big difference to the temperature inside your house.
You can buy big rolls of bubble-wrap from home centres, and tape it to your windows for some basic, reusable insulation.

As with any place where it's cold, it snows, and you drive, there are a few things you should look into during winter.
  • Snow tires - Often just a recommendation, but in the northern areas of Okayama prefecture, they may be a necessity.
  • Letting you car warm up - Depending on the age of your car, the oil you use, and the time you have, it may be worth letting your car run a bit before zooming off. This will also give you a chance to run the heater while parked, allowing you to avoid fighting off cold shivers while trying to drive
  • A bottle of hot water - before you leave the house, check if snow has accumulated on your car. Using hot water will clear off your windscreens and mirrors in seconds.