What is the cheapest short-term rental in Yokohama?

I’m currently living and studying in Chiba. In March, I‘ll start a 3-month internship in Yokohama. I’m searching for accommodation as cheap as possible. I don’t need anything fancy. Just ja small room with a bed/futon and access to a kitchen and bathroom. I’ve already looked in shared housing and common rental webpages but I wonder if there’s a even cheaper (and less fancy) alternative?