I don't know about Japan as a whole, but racequeens were one of my favorite things about being a racing driver! Here in the US and at many events in Europe, models either mark the driver's place on the grid or hold an umbrella over them to keep them out of the sun. Full-face helmets and Nomex are bloody hot in the summer....
Sometimes they're called gridgirls, or umbrella girls, but my favorite was grid mice. I still use that term! I thought it fitting because when the cars fire up, they scatter like mice!
Other countries have the grasped the concept, but Japan has it down pat.
By the way, this thread is nothing without pictures (hint hint!).