Nanachi is so-called "Final Form" - a survivor of ascension from the sixth level of the Abyss. Madness and/or death are not uncommon results of such an attempt but, due to certain circumstances, Nanachi was able to keep her personality and mental faculties intact, her body, however, was deformed beyond recognition.
Nanachi is presumed to be female, although her sex is never expressly stated and talking about herself Nanachi uses gender-neutral pronoun "oira".
Not much is known about Nanachi's past - she was born in the Far North region of Sereni, lost her family and home at a young age and was taken to the Abyss by treachery.
Nanachi looks very young but her vast knowledge of the physics and ecology of the Abyss seems to suggest she's lived there for quite a while. She also appears to be an accomplished healer with significant surgical skills and extensive knowledge of medicinal plants and such. Most of the time Nanachi is cool and reserved, keeping her distance both emotionally and physically. Her ironic attitude often borders on being sarcastic and even cynical, however behind this mask Nanachi hides a kind and gentle soul capable of deep compassion and selfless devotion. (Source: Wikipedia Japan)