A gauna/human hybrid created by Kunato Developments for fighting against the Gauna. Similar in size and appearance to a guardian, but having a gauna-like appearance, her prowess in combat is rivaled only by Nagate's. She becomes friends with Nagate and Izana, usually interacting with them at their house by a tentacle she sneaks by the vent system while her main body stays at her hangar.

Spoiler

Later it is revealed that Tsumugi was created from a sample of a Gauna with Hoshijiro's DNA.

(Source: Wikipedia)