Many FReepers made their “bug-out” kits after 9/11. Most of the same rules apply here.
I am the health and safety officer for my company here in Tokyo. Beginning tomorrow I am going to recommend strongly that everyone wear face masks everywhere outside the home, and try to make it mandatory in the office.
Additionally, I am going to get an ear-type thermometer and ensure that everyone gets their temperature checked when arriving at the office. Persons who feel they may have been exposed will be encouraged to telework to the greatest extent possible.
For Tokyoites, I see the daily commute as the biggest exposure risk because Tokyo trains are crowded beyond belief and a single infected person could conceivably infect half a crowded train car with devastating consequences.
On a more personal note, I have on hand, 60 liters of bottled water, more than 10 kilos of rice, an assortment of high protein foods including canned fish, refried beans, and a well stocked pantry filled with the usual stuff so if I have to stay at home and telework, I can do that too.