Don J. Modesto wrote:
"WAKA" means young. While Osensei was alive, Kisshomaru was the young'n. When he became Doshu, it was his son, the current Doshu. I'm betting HIS son, the 4th Doshu, is already affectionately being called WAKA as we speak.
When I last trained in Doshu`s class, at the Paris seminar this February, his son was one of his uke`s. He was referred to as waka sensei during the presentations at the end.