In this page, I show Comparison with sales price of apartment and rental fee in same ㎡
One is average sales price of used apartment / 70 ㎡.
Another is average rental fee of apartment / 70 ㎡ .
In this page, you can find which prefecture is reasonable compare with rental fee.
For example, in Ibaragi prefecture, sales price is 173 times higher than rental fee.
In Tokyo prefecture, sales price is 231 times higher than rental fee.
This means that you can purchase real estate at reasonable price in Ibaragi prefecture.
If you purchase in Ibaragi prefecture and rent out, you have higher chance to get high yield.