Board Thread:General Discussion/@comment-25642086-20141108072343/@comment-11269545-20141109223112

Mohrpheus wrote: Well, Isshin knew about both Auswählen and the Kaiser Gesang. Whether the Shinigami as a whole knew about them is unknown. Furthermore, we don't know how or for how long Isshin has known, though I suppose Ryuken is suspect.

Yamamoto and Mayuri's conversation earlier in the arc suggests that Yama didn't see this coming. Mayuri suspected, but they had nothing concrete to go on. isshin was married to an Echt Quincy