She is seen to encounter Aqua in Kingdom Hearts Birth by Sleep, the Keyblade warrior having previously rescued her granddaughter. At the Hollow Bastion library, she related to a young Kairi a story about the light and the birth of the darkness coveting the light.
Thanks to Kairi's heart being transplanted into Sora during the destruction of Destiny Islands, Sora was able to access Kairi's apparently lost memory of her grandmother telling her the story of light and darkness. Later, after Kairi is restored to completion, Sora, upon meeting Kairi in the Underwater Cavern in Traverse Town, acknowledges that there is a deeper meaning to this story, and stated that it was "more than just a fairytale".
Kairi's Grandma is a small, elderly woman with thick, grey hair tied into a bun. She is usually seen smiling pleasantly with her eyes closed, though the few times they are seen open, she is shown to have blue eyes like Kairi. She wears a sleeveless, purple dress with a white apron that has laces at the bottom, over it. She also wears a dark cloth tied around her neck, and a white ring on her left ring finger.
Kairi's Grandma first appears in terms of story chronology in Kingdom Hearts: Birth by Sleep. She finds Kairi after Aqua and Mickey saved her granddaughter from a group of Unversed. As they walk away, Kairi asks her grandma to tell her favorite story about the light and the darkness, with Aqua listening in the background.