Saga of Tanya the Evil (Evan)

Saga of Tanya the Evil, also known as Youjo Senki, is an ongoing light novel series by Carlo Zen revolving around a Japanese salaryman who has been reincarnated as Tanya Degurechaff in what is the equivalent of the Second Reich during WWI, except now there are mages. In her previous life, Tanya was a salaryman that fired workers for poor performance. One day he is pushed into the path of a train by a worker recently fired by him, and meets who he calls Being X (who is implied to be God). The salaryman starts arguing with Being X about him being God, bringing up the classic atheistic points. Being X decides to send him to this alternate universe WWI-era world, to make him struggle as an orphaned girl so he will find faith in God. Tanya is gifted with a large amount of magic and decides to join the military in hopes of gaining a comfortable life through working in the rear. She's very cold and ruthless both as a salaryman and as a child, firing many people over poor performance in her previous life, and employs very extreme training and punishments while training soldiers in her new life.

I'm gonna be honest, that last paragraph wasn't a very good elevator pitch, but I hope I got the general idea of this story across. There are lots of military tactics, war crimes, and bureaucracy in here that I skip over. Tanya acts like a monster in the story, but many people see it as love for her troops or devotion to her country when she really doesn't care about them and just wants to get a cushy office job. Ironically, the fact that she keeps getting results and victories for the empire means the generals keep sending her out to the frontlines. She claims to be a pacifist and is shown to not like fighting (although not in the "why can't we be friends" way but more in the "waste of human resources" way), but people like Erich von Rerugen (or Lergen) see her as a psycho who absolutely loves war due to her attempts to seem like the perfect soldier. 

There are other adaptations of the original light novel series that exist. The manga has absolutely gorgeous artwork and is my preferred way to read this series, but is way behind the light novel and gets scanlations at a slow rate. The anime is currently at one season and one movie. The anime is less focused on the story and more on the action. The anime's art style isn't something I really like. The manga is in between the two with a balance of dialogue and action. It has many comedic moments and gorgeous art that makes me prefer it over the other two versions. The light novel is very dense word-wise with a heavy focus on dialogue and less on the action. The artwork is even more beautiful compared to the other two but there's so little of it. The books have several hundred pages and should just be called novels instead. The manga and anime are much more digestible if you don't want to spend a whole lot of time reading. If you plan to watch the anime first, then if you decide you want more you should start from the beginning of the light novel or manga since there are things that the anime skips over.

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