Cheapest groceries in Tokyo

Where is the cheapest supermarket to buy groceries in Tokyo?

I'm looking for a combination of large selection and affordable price. I don't care if they carry Western food or not.

Where in Tokyo? There is no point giving you details of cheap supermarkets if it is going to cost you several hundred Yen each way in fares and maybe take an hour or two to get to and from.

I live in Nishi-Oi (Shinigawa), and I commute every day to Shibuya and Akihabara.

In years I am here I like two chain shops which I use to go.
Yamaya is good for pastas, canned food, wine, oil, and Imported food.
Here is the shops list.

http://www.yamaya.jp/pages/store/index.html#tokyo

Then HANAMASA which is good for meat, some cheeses and other imported stuffs.

Both do not have English website then if you do not speak Japanese use the Google translation, then copy and paste the Japanese address to easy find the location.

These shops serve also restaurants.

Please take a look at both and try to remember the prices to get the best, if you never went I suggest you really to take a look.

For vegetables and Japanese food is better you find local small shops which can be much cheaper to attract clients, they make regular offers.

At the end you should chech the shop like Hito Yokkado 7&i Seven & Holdings and go 45 minutes prior the closure and you will find meat, cooked food etc showing 50% discount every day.

I wish it helps.

here is the the hanamasa link I forgot to paste it...

http://www.hanamasa.co.jp/shop/index.html