Tonari no Maou

Natsuori Seno is an ordinary high school girl living in an ordinary country town. One day, however, a demon lord moves in next door, and her daily life changes forever! Natsuori can't stop fussing over the Demon Lord, as he discovers the joys of sales discounts, mail ordering, and joining the neighborhood association!

(Source: ComicWalker, translated)

Note: Chapter count includes 1 extra chapter.