Izumi is a character from the anime Garo: Crimson Moon, serving primarily as an informant. She is a knowledgeable figure to whom the onmyoji Seimei regularly goes for advice and guidance. Her character is based on the historical figure Izumi Shikibu, a renowned poetess from the mid-Heian period who is recognized as one of the Thirty-six Medieval Poetry Immortals. This real-world inspiration subtly informs her role as a source of wisdom within the story.

In her personal life, Izumi is depicted as a loyal friend. On one occasion, she attempts to help a friend who is experiencing marital problems, specifically regarding a husband known for being unfaithful. To aid her friend, Izumi enlists the help of the main characters Raikou and Kintoki. This action demonstrates her willingness to take practical steps to resolve the conflicts of those she cares about.

A significant part of Izumi's background involves a profound personal mistake that haunts her. A major event from her past, a broken promise made to a childhood friend, is directly responsible for the creation of a Horror that the protagonists must confront. The betrayal of trust that occurred when she failed to keep her word had devastating consequences, causing her friend's life to spiral downward and leading to tragedy that extended beyond just the loss of their friendship. This past failure is a core element of her character, demonstrating how unresolved guilt and childhood actions can have supernatural repercussions in the world of Garo. The narrative uses her story to explore themes of friendship, betrayal, and how the events of one's youth can profoundly shape the present.