Flee markets in Tokyo?

I'm looking for some large general flee markets in Tokyo. I'm in Japan until the end of September and my closest station is Shibuya Station.

I'm mostly looking to look around, but I am also looking for a cheap general kitchen knife and maybe some souvenirs.

If you have a suggestion, please list the dates and the location of the flee market.

Hope you can read Japanese:
http://www.winriver.net/tokyo/amusement-t/flea-t.html

there is one that i sometimes go at oikebajo-mae
its beside the horserace track. its open every saturday and sundays, except rainy weathers. I dont remember the exact place, i will look into it later