If Kato accepts new dogs readily, an older female would suit him fine. There are so many mature ladies in shelters waiting for a home.
We lost our beloved Morgan in 2012 when Otto was 4. Morgan was a very assertive female, stern taskmaster and 7 years old than Otto. He's hard headed dog but was never given a choice but to accept Morgan as his wicked stepmother from 8 weeks old. I've had shepherd friends come for walks with iron bitches were like Morgan was. Otto has made perfectly clear he does not having that in his life.
So we got a puppy and she's exactly what I asked her breeder for, athletic, brilliant, not afraid to stick up for herself but not looking to challenge Otto. Otto adores her.
Venus of Crooked Creek 1/26/13
Otto von Hena-C 05/23/08
Morgan Donnermond 08/04/01 to 9/28/12 Long Live the Queen!
I have duct tape and I am not afraid to use it.