She was humming their song and was blissfully unaware that the body had gone limp in her embrace.
The moment was just too perfect for her to notice.
Hone Onna, or 'Bone woman' is a japanese yokai who appears young and beautiful, but is in fact a rotten corpse. She exist solely to reunite with her former lover who is so happy to have her back that he does not notice anything wrong with her. Others might see her for what she is, but if their relationship goes unnoticed she will drain him for life and eventually kill him.