Apt or Budget Hostel / hotel

Hello there

I am looking to volunteer in Japan for 3 months and need to find inexpensive housing, on the Ginza train line. I want to be in a safe area that is well-lit and has small shops, boutiques, restaurants nearby. I ran across a couple of possibilities (Kangaroo Hotel) and a hostel along stop G18. Can you all point me in the right direction? Or make some recommendations? This place absolutely has to have Western-style showers and bathrooms (no public baths or squat toilets).

Since this is unpaid work, I need to be as budget-conscious as well. Thank you.

Where in Tokyo you will be doing your volunteer work? Commuting can be a hassle if you happen to choose a location on the opposite side of Tokyo. Generally speaking, G18 on Ginza Line, or areas like Asakusa and Ueno tend to have, yes, relatively inexpensive accommodation.

I have only read the description about Kangaroo Hotel on their website, but note the very small size of each room (or cubicle I might say) and the limited number of shower units on each floor.
http://kangaroohotel.jp/sisetsu.html

You might look into"weekly/monthly mansion" - those are small apartment units, furnished and with in-room bathroom/shower, and can be rented on a weekly/monthly basis. Please try some searches :)
For example (not meant as a recommendation), Asakusa location on this one:
http://www.wmt-tokyo.com/