In case you divorce your Japanese spouse what you should do is to notify the authority.
Unless you have a permanent resident visa you might have to leave Japan. Even though Japan is a member of the Hague Child Support Convention it is not easy to see the kids on zoom or something. If you fail to pay the child support it is more likely you can’t talk to your own kid. The guy below was even arrested as he entered his former wife’s house without permission to see his son.
But, there is a way not to fail to pay the child support. Even if you are in your country and have a kid in Japan you have to pay the child support to see your kids even on zoom.
The international funds transaction is kind of complicated and charge a lot of fees.
The loophole is to purchase the property already occupied by tenant.
You will gain the rent income right after the ownership is transferred. I will be a proxy of the property owner so technically you pay the child support. The domestic funds transaction is easy. I can transfer the funds to your ex. You will have a right to see you kids. If your ex don't show your kids to you even if you pay the child support your ex could be convicted.
Your kids grow very quickly. You will regret not seeing them too often in the future. Kids need a father. I know a lot of fatherless people. I don't mean to be mean but most of them are bad apples.