Oninaki Wiki

A Gee is a Fallen in Oninaki.

Horrific Fallen whose bodies are dominated by a grotesque maw. Their kiss confers all manner of debuffs, so don't stand right in front of them.
Research Log 2-1
The insides of these Fallen are made up of substances that reflect little to no light. My colleague mused that it gave one the feeling of being sucked into a starless sky—right before actually being sucked in (and eventually coming back).