It only took shoppers two hours to strip the shelves of instant food at the Tanaka supermarket in Tokyo's Kita Senju area on Thursday morning. Koike's request triggered a wave of panic among people who have seen the images of empty shelves in other cities around the world.
One shopper said she was grabbing food with a long shelf life because she's worried that the rules about going out will get stricter.
Staff at the supermarket began making announcements asking shoppers to refrain from buying more than they need.
An official from the Japan Chain Stores Association says there is no need to panic. Atsushi Inoue says there is enough food available, but if one person panic buys, others will follow and that will create shortages.
Supermarkets and convenience stores plan to remain open this weekend, but many stores will close. Shibuya's iconic 109 is one of many department stores that will be shut. Movie theaters and theme parks will remain locked.
Tokyo currently has just over 250 confirmed cases of the virus. Experts are worried that the infection route in some cases is unknown, and warn that the numbers could be about to spike again.
With the future uncertain, people in Tokyo are stocking up.