Maou-sama, Re Re Revenge!

Middle school girl Ooma Mada was the Demon Lord in her previous life. She (he) has but one lingering regret. And that was the fact she wasn't able to confess her feelings to Riri, her attendant, whom she loved in that previous life. A love that would never come true... or so she thought, when Riri somehow appeared before her eyes in this new life...!? A bright and pure rom-com spanning past and present lives, about a former Demon Lord who's at the mercy of the one she loves!

(Source: Shogakukan, translated)