Consider Korea. Two weeks ago, 28 cases, same as they had has for weeks. The current outbreak in confirmed cases only began growing one week ago, on Feb 19th.
The country is now entering lockdown, and some countries are banning flights from Korea.
If your flight leaves, say, tomorrow, you risk the same happening by the time you leave.
If it leaves further in the future, you have the good fortune of being able to wait and observe. If it gets worse you maybe able to get refunds on flights/hotels. Either directly or via cc. (As flights may be cancelled)
If it gets better, you can keep it. But if you leave now you’re taking a gamble you won’t have a lockdown before the end of it. This is moving fast, and japan is reporting new cases daily.
Note: the risk profile of being in a place is different from living in a place. If you live in a place you can just stay home. If you travel you have all manner of dependencies, and none of your usual supplies.
https://www.nytimes.com/2020/02/26/opinion/coronavirus-japan...
Japan has very poor rankings on press freedom, reporters are routinely fired for questioning the government, and Abe has a long history of being a dishonest, self-serving, authoritarian.
https://www.latimes.com/world/asia/la-fg-japan-press-freedom...
They should be responding like Korea has been, but instead are just ignoring the situation.
Be prepared for travel disruptions. My connecting flight was canceled when my destination country decided no more flights from not only China, but a few surrounding countries.
Had to buy alternative tickets last minute to take a detour and get where I wanted to go.
In my city, not on your itinerary, all elementary and junior high schools are being requested to close. All community volunteer oriented events and classes are being cancelled for whole month of March. All government employees are being asked to wear mask. All events in government buildings being asked to close.
Things are moving rapidly since government came back from long weekend.
I have noticed a high number of Chinese tourists in the Niseko region on vacation though and overheard some families from Hong Kong talking about vacationing outside of China to avoid the virus. Not sure this is something to be that worried about - I'll leave it up to you.
Tokyo is where it’s the worst, right now
On the other hand if you are young and fit and capable of following the standard precautions I don’t think you have too much to worry about.
I say this as I’m about to depart from Thailand for Taiwan
Or indirectly to other fit people who eventually down the line infects a high-risk person.
So I think it is quite selfish to expose yourself unnecessarily. I don't think we should stop everything we do, life still goes on, but just be considerate of others.
Why are you going to japan/what do you want to do there? If it's not essential for you to go, then it's probably an unnecessary risk. With how quickly the disease is spreading, 2 weeks is a long time for things to get worse, and there's always the risk of you becoming a vector for disease so it's more than just your own health to worry about in terms of safety.
https://wwwnc.cdc.gov/travel/notices/alert/coronavirus-japan