Quote Originally Posted by Beskar View Post
Northnovas was also called by that name. It is not wrong to presume there are multiple instances of names and the method of death could be due which character did it. The guard duty kills being that of ninja. We can only learn more about that from seeing more kills.
The ninja's seem to kill those on guard duty while the traitors kill in the victims room. However:

Watanabe Yumi (Olavi) entered his room. He was tired and in dire need of some sleep. He quickly undressed himself, placed his katana and his wakizashi in a corner of the room and went to bed.
Would indicate that he was doing something that night. Combined with the others it is a reasonable assumption. Perhaps next night will reveal more.