Japanese adult adoption, adopt a Gaijin

As far as I know, there is a legal adult adoption in Japan, which allows to adopt someone to the own family.

Is there also a possibility to adopt a non-Japanese citizen to the own family? I have heard only about Japanese who adopt among their own citizens, but how is it when a Japanese wants to adopt a Gaijin? Is there any possibility?

A legal adult adoption can be made between a Japanese citizen and non-Japanese citizen but is not automatically grant those adopted non Japanese citizen to gain Japanese citizenship.
Non Japanese citizen needs to take legal process to gain their Japanese citizenship.

Yes it's possible, but they have an extensive background check to make sure the Gaijin will be properly cared for. Things like a clean cage and plenty of room for exercise is paramount, as well as proper food and clean water for their dishes...