Saionji Touka

She is an underprivileged high school girl with an introverted personality, and she works part-time as a housekeeping maid every weekend.
Most unusual is the fact that she's actually a Battle maid, engaged in combat against an unidentified hostile force invading Earth, The fight against the unknown forces that started 10 years ago has now become a part of humanity's life and many private military organizations and vigilante groups exist, and she belongs to one of them...
What makes her different from the average PMC is that the president of her part-time company is crazy about maids' uniforms! All of her mission uniforms are maids' and butlers' uniforms, and she actually works as a dispatch maid on the side.

She has an inherent bad luck that is always with her, 'and she possesses an amazingly strong power', everything she attempts has a bad outcome and 'she can wield a giant crushing hammer with ease'.