You have an unique ability, have had for your whole over hundred year old life. You are an immortal (well almost) who's job is to give a second change to people who died for a good cause. This is how you meet Sei and then an adventure begins.
You as either a mother or a child, met the DMMd character and live with them until you grew up or became the character's new family. You alone is responsible for the finding of this character, can you do it?