Cost of food in Japan?

Question:

How much is the expense on food per month in Tokyo or Yokohama, Japan, if a person cooks the food at home and doesn't eat outside? As estimate is all I need. Thanks!

Answer:

It depends, but let's say it's about >20,000 Yen (250 USD.) give or take.
Experienced "money saver" could spend less than that. I guess.

However, if you are a stranger here in Japan, you should prepare some extra money for the first several months, because it'll take some time to know how to survive at minimum expense in the area. For the first several months, you would need to prepare some basic seasoning and stuff, you need to learn which store is cheaper, which meal is good enough, etc.