A never gave her actual name. She zombified after she got bit by a zombie, but before that she announced to the world her location, which she never did before. I'm pretty sure she was suffering from some mental issues or depression, but to be fair, being without human contact for nearly three full months can do that to a person. Satou, the first listener, succeeds A, the first host, and kills zombified A since that was A's dying wish.

B...I hate to break it to you, but I think your sister was A. B never lost to her sister because her sister would always use scissors in rock-paper-scissors. A always lost to her sister because she always used scissors, but one time she used rock and tied with her sister.