Maou no Hisho

The Demon King is awake at last and hellbent on world domination—but first he needs a secretary. He finds a human to organize his devilish plot, and she's perfect for the job. So perfect, in fact, that she's steadily losing her grip on her humanity. Thanks to her smarts, super skills, and secretarial wiles, it's only a matter of time before the Demon King's destructive dreams come true!

(Source: Seven Seas Entertainment)