I can probably suggest my real estate agents. Small company, but the guy I dealt with was very nice, still keeps in touch with me 2 years after I signed my lease.

Anyway, I'm out Yokohama way, so they service this area. Look up Matsuzato Real Estate via Google, and if you get in touch with them, ask for "Yasu". He speaks pretty good English, having lived in Hawaii for a while. Their website isn't very good - I don't think they update it, and they don't show many properties. If you let them know your specs directly, they'll hunt down places matching these criteria for you, which is awesome.

If you end up going for town, then I can recommend a company called S-Fit. Again, their website doesn't show much, but they are a very slick opperation, and only deal with apartment buildings that have generally been built in the last 10 years, so most of their places are really really nice.
The average rental price tag reflects this of course lol

Anyway, hunt around, there are quite a few agencies around, all equipped to deal with expats.