>>7571503Le tentacle eye-demon species of Nordic and Japanese folk lore, conjoin with dead bodies and control them afterwards, human body is the most perfect host they can get and so they will not ever change back, le eye named Koishi had the idea to activate the brain of the host instead of still letting it the eye in stand-by-mode control, she transferred her whole consciousness from her former brain and body to the human one, achieved new and stronger powers than her sister, but got autism in the process.
That's at least I would say of her origin.