Tsubaki Minashiro

Tsubaki is Soushi's younger sister and is half Festum because their mother, Saya, was assimilated while pregnant with her. Tsubaki spends life in the coagula within Valkyrie's Cave and serves as the core of the Brunhilde System. At the end of Dead Aggressor, Tsubaki must return to the cave because her body cannot survive for more than three months outside the Brunhilde System.