In Japan, there is a system of real estate registry.
Civil Code (民法＝minpo) stipulates below.
(Requirements of Perfection of Changes in Real Rights concerning Immovable properties)
Acquisitions of, losses of and changes in real rights concerning immovable properties may not be asserted against third parties, unless the same are registered pursuant to the applicable provisions of the Real Estate Registration Act (Law No. 123 of 2004) and other laws regarding registration.
Assumed that Mr A had an apartment.
June １st Mr A sold his property to Mr B.
But, Mr B did not register his name and address in real estate registry.
June 11th, Mr A sold his property to Mr C.
And Mr C hired judicial scrivener (shiho-shoshi lawyer) and registered his name and address in real estate registry.
In this case, Mr C’s property right is superior to Mr B’s property right.
Mr B can not claim his property right toward Mr C.
On the other hand, Mr C can claim his property right toward Mr B.
So, when you buy real estate in Japan, you have to register your property right ASAP.
And when you are going to buy real estate in Japan, you have to confirm if the seller has registered his property right in real estate registry.
So, you have to look into the content of real estate registry.
Now, you can see content of real estate registry via internet.
This is website of real estate registry.
This is written in Japanese language.
When you purchase real estate in Japan, I can look at this real estate registry for you.