There's not much around Mark Twain Middle School in Coney Island. A fire station across the street, some auto body shops. If you want something to eat, you have to walk a few blocks and then this is your only choice. I wasn't enthused upon entering, but inside I found a Russian deli of amazing variety and authenticity. They bake their own bread (I bought a high, narrow loaf of white; it was delicious), and have an enormous deli selection. They make the most of the small space; the shelves are chock full of goods and you could easily do your weekly shopping here (if you don't mind eating exclusively Russian fare). The clientele appears to be largely Russian; the signs are in Russian, with no translation.
The business is apparently quite an enterprise. They deliver bread to wholesalers and retailers, and ship to 40 states. The clerk said they had been there "a long time." But I think she just meant a long time in her way of looking at it.