It's been implied that Ameri's mother is the author of the manga that Iruma worked on (First Love Memories), that's why Ameri's family has the complete set. This means that her mother is human (and still in the human realm), and Ameri is half-human.
I... Wha....
That's a strange thing to learn from the comments. Was this foreshadowed in the Mafia spinoff?
In any case, I wonder if who that lady is. Since most of the characters involved are ones we already know, I bet it's a introduction of a new connected one. I just wonder whose connection will that be.
I know it is a long shot but I sure would love if it is someone who knows the ring demon. As it really feels like that guy only exists in Iruma heads atm.