Interesting thoughts. Maybe like you guys stated, there's a third twist to this whole "sister" angle/situation . The first was sister as in "nun" design with the 2nd being the revelation of a fake sister with the real one being locked up/shut down. Not sure if it has been brought up, but maybe a 3rd would be fake sister and real sister either being actual "sisters" or formerly one single entity? Witch did state that fake sister's identification code is the same. I'm reading that as her DNA? Not sure of the scientific validity but since this is a manga, they could loosely represent a conjoined/siamese twins situation and what appears to be fake sister's "tail" was actually the former cord/link or some remnant piece previously binding both of them together? Alternatively, real sister expelled fake sister out similar to kami(DB) and going from last week's spoilers, she now seeks to reabsorb her . In which case, there may still be a new final form of sister . Too many possible twists .