Japanese rice is a short-grain kind, and its texture is soft and sticky compared to long-grain rice. Calrose rice is medium-grain rice that is similar to Japanese rice and most well known in the US.
Calrose rice can be purchased at most grocery stores in the US. Either short or medium kind, they need to be soaked in water before cooking. It can be cooked in heavy pot with lid or rice cooker (suihanki).