[blimp]

most of the sites work pretty much the same way.
either you search geography wise or you search depending upon train line.
yokosuka is called 横須賀 or 横須賀市. the area around tokyo including yokosuka is usually called kanto 関東 or shutoken 首都圏。　the province of yokosuka is called kanagawa-ken 神奈川県。 unfortunately i don't know the train lines too well down there as i don't live to close to yokosuka.

then again, using the sites i referred to will most likely not find you a semi-furnished flat.