Isekai Tensei shite Majo ni Natta node Slow Life wo Okuritai no ni Maou ga Nigashite Kuremasen

Miya is a hard-working woman with a good job as a secretary. One day, she lost her life and was reborn in another world as Miya of the demon tribe! She got a job at the Demon King's castle and became a secretary again, but when the Demon Lord treated her too roughly, she quit the job in anger. She moved to the human world as the witch Miriam, and enjoyed a slow and carefree life while being pampered by her knights and apprentices. But then the Demon Lord attacked!

(Source: Ura Sunday, translated)