You can also connect to linkedin.com
Linkedin is a social Media website for Professional People.
It does not list Japanese phonenumbers like historic Whitepages
but profiles of individual people.
Connected to Linkedin you can send messages
to people from Japan you found.
Linkedin was acquired by Microsoft.
As of 2020 may 2.692.000 people from Japan
are connected to Linkedin.
More on the history of Microsoft
on the Brand Portal VB.com