I think it's a "wait and see" situation.
My sister and her husband (both doctors) are going in a month. They are going to visit their son who lives there and teaches English - except they closed all schools today for a month. When I spoke to her last weekend, she didn't seem too concerned but I think she might be secretly a bit worried. It seems that Japan is one of the areas that is growing and I predict that my sister could have a change in plans as things develop. I'm gonna see her this weekend and I'll see if they have any more insight on this.
This is a pretty good website that shows the daily changes. It updates every day at about 4pm pacific.
https://www.worldometers.info/coronavirus/