Girl from Phantasia

One day, Akihiro Otsuki encounters a mysterious beauty named Maron. She claims to be a "guardian" protecting "Fantasia," a world where magical beings have fled. However... she starts living with Akihiro without his permission, and after a battle, she blows off the roof—trouble after trouble!? Serialized from 1992 to 1996, 5 volumes in total.