Natsumi Mizuki is a fourth-grade student who is bound for England, much to her dismay. She has one night alone until joining her parents who are already abroad, but when a baby materialized out of her television in the midst of a lightning storm, her plans quickly change! The baby, it seems, is her own child who was mysteriously transported into young Natsumi's life from fifteen years in the future; and no one, not even herself in the future, knows how to return little Mirai to her proper time. Her aunt wants nothing to do with child raising and Natsumi has plenty of her own problems to deal with as a fourth grader, but she must now attempt to raise a child, as a child, and keep Mirai's existence hidden from nosy neighbors and others alike!
Miyu's parents have big dreams: her mother wants to explore the universe and meet aliens, and her father wants to develop a new space shuttle. In order to accomplish their goals they decide to work at NASA; but due to their inevitably busy schedules, Miyu is sent to live with a friend of the family. On the day she arrives at her new home, her caretaker leaves on a religious pilgrimage, leaving her alone with his son Kanata. To top it off, an alien baby crashes into the house that night! The ship is too damaged to fly so the baby and his pet/baby sitter decide to live with Miyu and Kanata until help arrives, whenever that may be. How can two unrelated middle school kids learn to live together while raising a baby that insists on calling them mom and dad?
Both of these shows are about kids that are taking care of children. In Daa! Daa! Daa! the baby is from outer space and in Mama is a 4th Grader the baby is from the future but both of these babies are place in the care of people that are still children themselves.