Marumi Oki is a supporting character introduced in the second season of the anime In/Spectre. She is the girlfriend of Kazuyuki Konno, who works as an apartment building superintendent or property manager. Marumi is cheerful, straightforward, and outspoken by nature, bringing a warm and everyday energy to the story. She becomes deeply curious about Rokka Sakuragawa after Rokka moves into a notoriously ill-fated apartment unit without any apparent concern for its dark history. Marumi and Kazuyuki initially meet Rokka when she saves a child from being hit by a truck and appears completely unharmed. They later invite her for drinks and a light dinner, during which Rokka explains her reasons for moving in, including her determination to separate her beloved cousin from his girlfriend. Marumi and Kazuyuki develop a friendly rapport with Rokka and later interact with Kotoko Iwanaga and Kuro Sakuragawa when they come searching for Rokka. Marumi’s role in the narrative is that of a grounded, ordinary human who provides a contrast to the supernatural events and the extraordinary abilities of the main characters. Her relationship with Kazuyuki is portrayed as cozy and realistic, and she serves as a sympathetic listener and observer within the local community. While she does not possess any notable supernatural powers or abilities, her perceptiveness and open-mindedness allow her to accept the logical explanations Kotoko offers for the apartment’s supposed curse. She does not undergo significant personal development over the course of the story, but she contributes to the atmosphere of normalcy and human connection that balances the series’ more fantastical elements.