Mama is a 4th Grader

Natsumi Mizuki is a fourth-grade girl whose parents have left for London. Her Aunt Izumi moves in with her, but Izumi is an aspiring manga writer chasing her first big break and has little patience for a baby that materializes on Natsumi’s first night alone. The infant is named Mirai, and her mother is Natsumi, though fifteen years older. Somehow Mirai has traveled back in time. Now the younger Natsumi must raise Mirai while keeping her own fourth-grade life from unraveling and keeping Mirai-chan a secret from everyone. She counts on Izumi’s dubious help and a cache of futuristic baby-care gadgets.