The Vexations of a Shut-In Vampire Princess, Vol. 9 (light novel‪)‬

One team, two pint-sized powerhouses! After narrowly avoiding death at the hands of Tremolo Parcostella, Komari awakens to the sight of her mortal enemy, Spica La Gemini, and the rest of Inverse Moon. Instead of killing Komari on the spot, however, Spica hits her with an outrageous proposal: team up to take down Star Citadel. The two form an uneasy alliance and head for the prosperous mining city of Neoplus, where Star Citadel is supposedly operating behind the scenes. But will their combined might be enough to usurp the most powerful organization in the Netherworld?