Mari is a student at Yamazakura Elementary School and a classmate of the main characters Ako Ozora, Reiko Sakuma, and Sho Komoto. She appears as a supporting character in the anime series Thriller Restaurant. Unlike Ako and Reiko, who are frequently drawn into supernatural events, Mari shows little enthusiasm for ghost stories and does not actively seek out the eerie occurrences that surround her friends. Her personality is more grounded and ordinary, making her a contrast to the more curious and sometimes reckless behavior of the others.

Her role in the story is primarily as a friend and peer who participates in school activities alongside the main group. In one instance, she joins Ako, Reiko, and Sho in making a Kikimora puppet for a class play, witnessing the strange events that unfold when Reiko breathes life into it. Mari does not take a leading role in investigating the paranormal; instead, she serves as a typical classmate who is present during the everyday school life that frames the anthology’s horror segments.

A notable aspect of Mari’s character is her quiet crush on Sho, the mysterious transfer student who collects ghost stories. This subtle romantic interest does not drive the plot but adds a layer of personal motivation to her interactions with the group. She is not shown to have any special abilities or deep character development over the course of the series; her presence remains consistent as a supportive and relatively unflappable friend. Her motivations are simple: she wants to spend time with her friends and maintain a normal school life, often detached from the more intense supernatural experiences that the others confront.