A very shy and reticent 16 year old bibliophile from Majima Academy. A member of the Library Committee, she is a school librarian with her position in the committee as the secretary. Elsie first encounters Shiori and detects a spirit inside of her when she visits the library. After bringing Keima and investigating, they learn despite having an amazing ability to memorize all of the books of the library, Shiori is too shy to speak and takes to long to respond to others. The reason for this because as a child, she was shy to speak up as she was afraid of being misunderstood which is why it takes so long for her to reply. Yet it was also the same time that she discovers her love for books which was form of escape for her where she felt it wasn't necessary to talk to people as long as she had books. Because he doesn't know what she's thinking, Keima purposely angers Shiori in their encounters by writing library books or explaining why books are useless in today's age which causes her speaks out her mind in anger to the point she confusingly speaks out her inner thoughts. Thanks to this he is able to speak to Shiori normally. But when she learns the Library Committee are planning to dispose books for a media room, she locks and barricades the library as a protest. It is then when Keima joins her and confronts her with the truth that she isn't barricading herself to protect her books but herself to the world as she always wanted to talk to people but is afraid of being misunderstood. However Keima vows to be her support she needs and kisses her, finally forcing the spirit out. With her fears gone, Shiori is finally able to speak for herself and explains her reason to Library Committee, who agree to discuss about the fate of the disposed books.
After the incident, Shiori is able to speak to people normally and continues her work at the library. However, she has some faint memories of her encounters with Keima and writes a story on what she remembers. During his search for the goddesses, Keima suspects Shiori is a host as the story she wrote is similar to their encounters before and is mad over the rumors of him and Kanon by having the character based on him killed. Later, it is revealed she is the host of Goddess Minerva but unlike the others, Minerva can exists outside of Shiori's body. However, Shiori is unaware who she is and Minerva is too shy to speak to her. Keima tries to repair their relationship after Shiori catches cross-dressing while he was dating Yui, by revealing he does remember their time together and helps her write a story for the school festival and for him to read. After suffering from Writer's Block, Shiori, with the help of Minerva, manages to write a story of her love for books but especially her love for Keima. Keima reads the story, telling her he enjoyed it and kisses her on the cheek, which restore Minerva's powers. After Keima leaves but not before giving her magical bracelet, Minerva properly introduces herself to Shiori.
The cause of Shiori's negative emotions was her wish to speak out to others but fears of being misunderstood.