[Kitsu]

Spoiler for Epi1:

My theory is:
Natsuhi committed at least one murder of the first twilight maybe Krauss. It was a murder cause by wrath, fury or another strong emotion. After killing she hurried back to her room and was nervous and shaked unable to unlock her own door.
Either she has a disorder or she was just really angry which caused the lack of memory, which is a possibility as well.