The last sentence doesn’t quite make sense, could you explain what you want to say? “that crazy popular in Japan.”

In the US, we often use the expression "it's going around" to say that many people are getting sick with a certain virus at this time of the year. It's a very common expression that will add a little native touch to your speech or writing. When speaking of getting better, you can also use the phrase, "I'm recovering", which means the same thing.