The Perfect Insider is based on the Mephisto Award winning mystery novel Everything Becomes F: The Perfect Insider by Hiroshi Mori. Unlike most anime novel adaptations, which are based on light novels (Japan’s equivalent of YA), Everything Becomes F is geared towards adults, and it shows in the sensibilities of the characters, the subject matter handled, and the ages of everyone involved.
Professor Souhei Saikawa and his students visit a remote island as part of a university outing, but also because it’s part of a research facility housing the infamous genius, Dr. Shiki Magata. Fifteen years ago, when Magata was a child she killed her parents, but was found non compos mentis (not of sound mind).
Instead of a more conventional way of isolating her or integrating her back in society, it was decided to shut her away in this research facility where she could work to her heart’s content. The benefits of her genius could still be reaped and she would be unable to kill again. For her part, Magata insists that she never killed her own parents, but that the deed was done by a doll.