Shiina Kagari is the adopted daughter of Shiina Mayuri in 2036 in the Beta 1.129848% World Line. In the year 2028, Mayuri is working at a children's orphanage and given custody of a young girl. Because of the war the girl's family register was lost and her true full name unknown. Over time the child grew to view and love Mayuri as her true mother. Mayuri gave her the name "Kagari" -most likely in reference to "kagaribi（篝火?)", meaning bonfire-, with the wish that Kagari would be a shining light to everyone no matter how dark the world line is. In 2034, she was adopted by Mayuri. From 2028 to 2036, for eight years, Kagari was in Mayuri's care until the events of Epigraph of the Closed Curve, at which point she time traveled with Amane Suzuha to the past.