hostels near shinjuku or shibuya?

well i'm planing to go to japan with like two other friends of mine this summer for about a month. we want to be somewhere around or at shinjuku or shibuya...??? but nope of us have any luck at all in finding one...and when we did..most of them don't allow us to stay up to a month...=( could anyone please help...thank you very much....

Have you checked apartments?

Sakura House :
http://www.sakura-house.com/
J&F Apartments :
http://www.jafnet.co.jp/plaza/contentse/e_top.htm
(Scroll down to the Serviced Apartment section)

Or
International Youth Hostel :
http://www.tokyo-ih.jp/en/index.html

yea i thought about apartment...but then they need like despoit money and key money and all other stuff...so i don't know...but thank you very much for your reply

Serviced Apartments (for tourists), in general, do not require "key money" and even if they ask "deposit," it will return when you leave.

In Tokyo as in many big towns one can stay in neighbourhoods relatively far from the centre and commute to downtown by subways and trains.
are you really planning to stay one full month in Tokyo? unlike London, Rome, Paris etc. there isn't that many historical sights in Tokyo for a month. As for shopping, from boutiques to big department stores to electronic stuff, Osaka especially but also other major towns have lots to offer too. Why not stay 1 1/2 weeks max in Tokyo and 2 1/2 weeks in 2 or 3 other areas of Japan?

lol yeah i'm staying for a month..and yeah i plan to go somewhere else too..but not so sure yet hahaha.....oh yeah...one more question...???? since me and my friends are from the U.S...do we need a visa to go to japan for a month or no...cause i'm confuse...some people told me i need one..but then other were like only if you stay there for more then 90 days..??

You don't need a visa if you are from the US and staying in Japan for less than 90 days.

Sorry, forgot to post the official link for the Japanese Ministry of Foreign Affairs:

http://www.mofa.go.jp/j_info/visit/visa/02.html

there are hostels and cheap places in Ueno and Asakusa. from these places, especially Ueno, it is very easy to go to any of the major neighbourhoods by the JR Yamanote loop line and/ or subways. It only takes 20-30 minutes from Ueno to Shinjuku etc.
you don't need a visa if you are an American citizen. If you live in the USA but don't have yet your US citizenship you may need a visa depending on where you were born. Where people are confused is the fact that all tourists need a temporary visitor visa. people from countries (USA, Canada, France etc.)that don't need to get a visa from the Japanese embassy in their home country, get that one when they go through immigration after landing in Japan.