To send a package home you will have 4 choices:
1 EMS Service: Fastest and most expensive 3 days (2000yen a kilo)
2 Airmail:Also quite expensive, around 7 days (2500 a kilo)
3 Surface Mail: Cheapest but takes around 2 month, this is best if you will send heavy stuff (1500a kilo but gets cheaper if you send more)
What most people dont know that there is another alternative thats called Economy Air.
4 SAL: Economy Airlmail takes around 2 weeks but is not so much cheaper unless: Your package is 2kg or under and the total length is not more than 90cm. (1000yen a kilo if 2kg or under otherwise 2000 to 2500 a kilo)
I recommend working with small packages and SAL as they are cheap (around 1000yen a Kilo) and the time is reasonable (2weeks).
If you send alot take the surface mail
You can off course wrap it in you own package!
You can check the prices and everything else here:
nternational Parcel Post - Japan Post
i just checked, EMS might be cheaper than airmail!