Sou Hazuki 
Moon Blossom Asura: The Ruthless Reincarnated Mercenary Forms the Ultimate Army Volume 1 [EPUB ebook] 

In her past life, Asura was a soldier of fortune who lived for the battle above all else. So when she reincarnates into a world with magic, she gladly takes up the mercenary’s path for a second time. Drawing upon her battle-hardened experience, she forms the mercenary group Moon Blossom and pioneers the concept of the soldier-mage: magic users who also fight with the skills and training of military soldiers. Roaming the battlefields of this new world, Moon Blossom—led by Asura and her unrivaled schemes, ruthlessness, and tactical ingenuity—earns a fearsome reputation. Thus the curtain rises on the dark fantasy epic of a young girl who is spoken of in fearful whispers as “The Silver Demon”!