According to Japanese mythology, Japanese nobles are descended from dragons, who instinctively know their soulmates. Once they have met and been accepted by their chosen mate, their physical and mental health depends on the continued presence of their mate. Fujino Shizuru is probably of noble blood, if her skill in the traditional arts is anything to go by. Met Natsuki, had issues remembering that other people mattered, but was kept relatively stable by Natsuki's presence. Note that she didn't snap until she was blatantly rejected by Natsuki, and was brought back to sanity by same's acceptance. Diagnosis: Her Inner Dragon was bashing its head against the wall.