The Guardian of the Devils

The job of babysitting monsters and creatures.. that is the role of a "Mamori-bito"! A hundred years ago, a gigantic dragon suddenly appeared, capable of swallowing entire nations whole. In search of the treasure slumbering within it, people began venturing into the dragon’s belly, where monsters ran rampant. Ariaris, a hopeless ranger who found herself unable to return to the surface from inside the dragon, is taken in by Lumon, who has lived there for a long time and works as a "Mamoribito", and ends up helping to look after the monsters’ children!? Whether human or monster, children are all a handful! A parenting × fantasy tale featuring rookie Mamoribito Ariaris! (Source: Shounen Gahousha, translated)