Rieko Hinaga (Hinga Rieko 日永 梨枝子) is an old lady, and the grandmother of Airi, who lives in the countryside. Rieko is very caring for her granddaughter.
She is like any old grandmother of the countryside, kind and gentle. At her age, she felt lonely, as her friends and family have moved away or passed away over the years. This created a gap in her heart, where the spirit entered. However the spirit left easily on Elsie's plea, after learning that Rieko cannot have children anymore. Accepting the loneliness, Rieko continues her days.
While Keima confronts Rieko's spirit, he encounters her child-self and her teenage-self. Her child-self looks exactly like Airi, while the teenage self looks more beautiful.