At first Enji was indifferent to the unexpected green baby. Too busy training his own chosen child to succeed him. Then years went by, he grown fond of the child. Especially, for his contagious smile. Unfortunately, the boy brought in his own problems: the fact that he was quirkless, gets in gets into trouble and attracts the strangest people... At least he's cute. (baby swap AU)

Misfortune befalls a young hanyou child and was sealed away along with a certain jewel. 500 years past and team of exorcists on a mission to find an innocence found the child and broke the seal and freed the child. But their joy was short live when a new stronger enemy appears far more powerful than the Earl could ever be.

The title said it all. This is a spin-off of new guardian, new world new and new mission. Everyone was getting ready for Christmas and was all excited. But then some familiar demons dropped in to join the fun. Will this be a Christmas to remember or turn to tragedy?