Ai is the main character and a 12-year-old gravekeeper, taking on the job after her mother passed away. She is quite naive, but cares a lot about others. According to her late mother, Lady Alfa, her father was called Hampnie Hambart, who somehow is the same alias used by her traveling companion, although he claims he never had a daughter, but she decides to follow him on his journey nonetheless to learn how the world became in its current state. Hoping to save mankind that God has abandoned. Ai was raised in a "village of the deceased" by her foster parents, Yōki and Anna. As the child of a gravekeeper and a human, Ai is arguably the last child born in the world, where ordinary children stopped being conceived three years before her birth. This and the fact that she has emotions is what make her different from the other gravekeepers.