Not sure why you're being downvoted. That's a valid question.

First, I live in Japan. Been here for over 25 years. So, here's a first hand point of view, but anecdotal. So, take it as you like...

Most people are growing up and moving to the bigger cities, because of education and because of jobs. If you want a very good job here in Japan, you need to try to go to a very good university.

If you are born just outside of a bigger town, or within 1 to 1.5 hr trip into a bigger town, then you'll likely travel to school by train and bus. You might even stay in this outer circle of homes when you get a job. That seems to be a kind of invisible "circle" where people tend to think "inside this circle, I can travel for school or work, but outside this circle, I'd be better off moving". Mostly that idea comes from two things: the time spent traveling and transportation costs -- you start to spend as much on trains and busses as you might for a cheaper apartment.

The further you are born outside that "invisible circle", you are much more likely to leave home for high school and then college, and then you are more likely to job hunt in bigger cities where there are more choices. It becomes too expensive to travel 2+ hours for every job interview.

So, in short, the countryside IS emptying out. The younger people are leaving for education and work, and the older folks continue to live there until they pass away... so the smaller towns and villages are emptying out. Thus the very large increase in "akiya", empty houses.

NOW, the "people are moving to the countryside" is a kind of YouTube influencer thing where there was a wave of non-Japanese people making videos about how cheap it is to buy one of these akiya in the countryside and improve them. So, those videos make it sound like people are rushing to the countryside to buy houses, but in fact, not many people are. Japanese people generally won't, because it's actually TOO expensive to renovate an old house, the yearly tax on houses is expensive, and then it's a nightmare to travel 30+ minutes every time you want to get groceries or look for new clothes. (I lived in one of these middle-of-nowhere villages for three years. Beautiful place, but took about 40 minutes to go get groceries, get to the nearest train station, or rent a movie!) Japanese people (well middle-age and up) start to worry about retirement and old age... and it's considered general knowledge that living in the countryside makes it extremely hard to visit the doctor, get medical help, get groceries, and such, especially when they are encouraged to turn in their driver's license (for people over 80) and there might only be one bus an hour into town! (Such as in the village I lived in.)

So, yes, there are two narratives on the internet about the Japanese countryside -- it's being bought up and renovated, CHEAP!, and it's emptying out. The later is the reality.