Tokyo metropolitan district pass(TMDP), called Tokunai pass in Japanese is a one day pass which allows unlimited rides on local and rapid JR East trains (excluding reserved seats) within the 23 Special Wards of Tokyo.
23 special wards cover major stations in Tokyo such as Asakusa, Shinjuku, Shibuya, Roppongi, Ginza, Akihabara, Ikebukuro and of course Tokyo station. However, TMDP is valid only for JR stations in these 23 special wards, which means Asakusa, Roppongi and Ginza which are not served by JR are not valid for this pass.
The areas which can be used are:
1)Chuo and Sobu main lines between Nishi-Ogikubo and Koiwa.
2)Yamanote line
3)Saikyo line between Osaki and Ukima-funado
4)Keihin Tohoku line between Kamata and Akabane
5)Keiyo line between Tokyo and Kasai Rinkai-koen
6) Shonan-Shinjuku line between Nishi-Oi and Akabane
7) Joban and Ueno Tokyo line between Kamata and Kanamachi
Current price is JPY 760 and it can be bought at ticket machines and ticket offices located at JR East stations inside 23 special wards. However, please be aware when you buy the ticket at ticket machine, the validity of the pass is the day of the purchase, which means you cannot buy the pass for tomorrow.
There is also a pass which covers JR, Tokyo Metro, Toei Subway within 23 special wards too. The price is JPY 1600.