Rin Mashiki is the mother of Miharu Mashiki and Miharu's deceased twin sister, Misora Mashiki. She appears specifically during the February and March storylines when Miharu is hospitalized, her presence directly tied to her daughter's struggle with the same inherited heart condition that proved fatal for Misora during childhood. Rin's role centers on providing family caregiving and support throughout Miharu's medical treatment. Her documented appearances remain confined to these events within the original anime series.