There's a Demon Lord on the Floor (フロアに魔王がいます, Furoa ni Maou ga Imasu) is a Japanese manga series written by Hato and drawn by Kawakami Masaki. It has been serialized in Monthly Comic Alive since 2014. Seven Seas has licensed it for release in English.
Amon Patricia is a Demon Lord who ruled the Demon World but after just barely escaping the Clan of Light finds her way to the Human World. Now there, she goes about searching for work and starts by looking at a family restaurant by the name of "Humming Dining" . With her seemingly bottomless appetite and love of our hero's food, will our hero be able to keep his sanity as he goes about making her an exemplary employee AND fill her stomach?!