You can buy marmite by mail order from:
http://www.fbcusa.com
They are the Foreign Buyers Club.....in fact you can buy marmite off of Amazon Japan via FBC.
There used to be a shop in Nagoya called Seijo Ishii that stocked marmite but of late I haven't seen it in the shops.
Hope this helps. They are only the tiny jars BTW.
When I go home to England my step mum buys me a catering tub of Marmite from the Cash and Carry for me to take back to Japan :)
Best wishes
Lorraine
