... Apparently he's a Siberian Forest Cat, or something equally odd. ...
The Siberian is one of three breeds of Forest Cat, which are believed to be the ancestors of all long haired breeds. The other two are the Maine Coon, and the Norwegian Forest Cat (the only one of the three with Forest Cat actually in the name).
I reckon Kai is related to one (or more!) of these, because he has a lot of the features, the ruff around the neck, long legs, big paws etc
That chap is a fine looking cat though, lovely colouring.