1. Mobile phone
I think I win the prize here ... I don't have one at all in Japan so cost is 0 yen per year
I have a landline phone both at work and home, and email access at both places while
my wife has a smart phone (on a low cost ~1100 yen per month plan) so I can get by w/out.
Unfortunately it seems like there is now a change underway whereby many transactions
(banks etc.) will require you to have a phone as well as email access. I plan to buy a cheap phone
in the UK and then get a UK SIM on a cheap pay-as-you-go basis (e.g. through giff-gaff) , with expected
running cost < 2000 yen per year.
2. Electricity
Before wife (who requires a little luxury) and baby goats arrived I lived a very stripped down existence
that required very little electricity - I used to pay about 150 yen a month for consumption cost.
How did I do that ? I didn't have a t.v. and there was no air conditioning installed where I was living.
I also didn't have a fridge, but lived next to a supermarket that was open very late and effectively acted
as my refridgerator. You can also consider charging things like ketai denwa /laptops etc. at work.
3. Food
Hasn't had much of a mention I guess but food is the one fixed cost we all have to pay.
In terms of Japanese food you can reduce your costs by working out what time the staff
go around your supermarket putting the reduced stickers on. For those of you from the UK (probably
applies to some other countries as well) there is a way to offset your costs if you are travelling home
anyway by making sure to buy and bring back food that will keep / has value (many foods are much
cheaper in the UK). I bring back about a year's worth of cheese, plenty of smoked salmon and breakfast
cereals when I go - I would estimate I maybe get a 7000~10,000 yen saving per suitcase without trying too hard.
Same probably applies to children's clothes which are very cheap in the UK, especially around the back-to-school
period in August. This is helped by the fact that Japanese Shogakko don't seem to have a uniform policy.