Flea Markets Ueno Tokyo April 2015

Hello,
I am visiting Tokyo from April 4th-7th 2015. I would like to visit Ueno Sakura festival- when is the best time to go and when are the flea markets?
Are there any other flea markets in Tokyo during this period?
Thanks in advance for your advise!

Do you want to see antique market?
Many of them, It will be held on Saturday and Sunday.
My recommendation is antique narket that takes place in Tomioka Hachiman Shrine in April 5.
Oi Racecourse is opened in the 4th and the 5th, abundant variety.
The 5th is also open Yasukuni Shrine antique maeket and Oedo antique maeket of Tokyo International Forum.
Antique market of Ueno do not know whether is opened.
If Used clothes flea market, will be held in Shinjuku Chuo(Central) Park on April 4.
http://www.jnto.go.jp/eng/arrange/travel/practical/kottou.html
http://tokyocheapo.com/shopping-2/fashion/top-tokyo-flea-markets/