Nanachi usually maintains a cool and reserved attitude, keeping others at a distance both emotionally and physically. Their demeanor often leans toward sarcasm or even cynicism. However, beneath this behaviour lies a kind and gentle soul, capable of profound compassion and selfless devotion. Despite this, Nanachi is easily embarrassed by compliments, particularly when called "fluffy," and show shyness when being petted, frequently happening by Reg.

 They're getting called "fluffy" for a reason — Nanachi is covered with medium tan fur, with light tan covering the insides of their ears and belly. Nanachi also exhibits several animal-like traits, including a cat-like mouth with small fangs, yellow eyes with horizontal pupils and erect bunny ears. Their fingers, though stubby, are surprisingly agile, reflecting their considerable artistic skill. This appearence, although very cute, raises a question: who is Nanachi?

 Nanachi was born in the far north of Sereny and lost their family at a young age before being taken to The Abyss by Bondrewd, a White Whistle Delver, along with other orphaned children. Bondrewd experimented on these children to negate The Curse of the Abyss, using Nanachi and their close friend Mitty as test subjects. The experiment left both Nanachi and Mitty permanently disfigured as Narehate, with Mitty becoming immortal and Nanachi gaining immune to the Curse of the Abyss. Unable to endure Mitty's suffering any longer, Nanachi escaped with her to the 4th Layer, where they lived in a secluded hideout. Unlike most other Narehate, they still retained a sound mind. Possessing vast knowledge of The Abyss (it's ecosystem, vegetation, and even the use of the medicines), Nanachi became a member of the Riko's team and took on a journey to the bottom of The Abyss.

 Judging Nanachi's age is difficult, given that time flows very differently in the Abyss; however, before the experiment began, their age was similar to Riko's. Despite this, Nanachi is reasonable and observant, unlike their companions. On top of top-notch tracking and stalking skills, since becoming a Narehate, Nanachi has been able to see the flow of The Force Field: a mysterious force behind the ailments that human beings suffer, upon attempting to ascend from The Abyss. They also shown to be artistically talented, having demonstrated excellent ability in drawing.