If this is anything like mine you need to be aware that they don't mean "cup" as in the imperial measurement of volume. They use it to mean "scoop" which is almost exactly 3/4 of a cup. It's based on some ancient Japanese measurement of rice.
K.T.NI misplaced it for a while and a used a 3/4 Cup measuring cup instead. That did work out fine, but the included one is much better/precise and had markings for 1/2 cup, etc. Treasure it.
PersonmanIt's 180mL to be exact. In Japanese the measurement is called one "go." It was thought to be the appropriate amount of rice for one person for one day.