Is it common to own two houses in Japan?

One in Tokyo and another in the country side?

Tokyo has the lowest home ownership rate in the country. Most people rent. So no, it isn't common. Some people own multiple properties, sure, but even among people who can afford a second home I think you'll find that most only have one.

It also depends on which type of accommodation you are talking about. I'm aware that some smaller units built during the 80's bubble in skiing locations can be extremely cheap (like under $20,000 USD) due to an oversupply and body corp fees.

It depends on your definition of "common". There are numerous people who own a "bessou" (resort house), and there are "resort house areas" where management is available. Many are indeed full, and still building.

Also, those who don't own a second house may have the impression that it is a huge luxury, but the truth is that it's not necessarily so. Building a weekend house in the middle of nowhere doesn't cost you much. The hard part is maintaining it, but you don't realize that when you build one. Some might use it as their permanent home after retirement, while others sell it after their lifestyle changes for one reason or another.

In other cases, people may inherit houses from their deceased parents/relatives, and use it as a second house. Perhaps off-topic, many rent second homes for various reasons.

Would you like to tell us why you ask?

I appreciate the detailed explanation. It�fs for a social studies research I�fm doing for school. Thanks a lot for your help.

Hi again,

If it's for school, this government report might be interesting. It's in Japanese, but I'll just post it as proof.
https://www.stat.go.jp/data/jyutaku/2018/pdf/kihon_gaiyou.pdf

It is a research that the Japanese government announces every 5 years, and this one is the latest, which was conducted in 2018. According to this report, among ordinary households (meaning residents including families and single persons but not boarding houses and such), 0.7% own either a secondary housing or vacation housing.

Also, just for reference, here are some old charts from 2008.
https://www.stat.go.jp/data/jyutaku/2008/nihon/9_1.html

Chart 9-1 shows percentages depending on the age, starting from "younger than 25" to "75 or older". The blue line is those who own housing. Red is those who own housing they currently live in. Green is those who own housing they don't currently live in (which includes housing of all kinds, and not just vacation houses).

Chart 9-5 shoes percentages depending on the annual income per household, starting from "less than 2 million yen" to "20 million yen or more".

Keep in mind that "housing" does not necessarily mean "house" but could also be an apartment unit. In fact, there are many vacation housing in the form of a resort condominium.

Hope it helps.