Mahou Shoujo nara 1105-goushitsu ni Imasu. There is a magical girl in room 1105.

Synopsis

Junior high student Mitama suddenly got chosen as a Magical Girl! As a result, The Great Demon King Jeddo's plan of bringing despair to the Earth got stopped in a mere 12 pages! However, this was only the beginning of their legendary everyday life where a Magical Girl and a Demon King live under the same roof! Everybody, get in there! A Slice of life comedy is about to start! (Source: MU)