Shioriko Mifune is a first-year student at Nijigasaki High School and a member of the school idol club. She initially served on the student council before succeeding Setsuna Yuki as its president. She is also part of the subunit R3BIRTH with Zhong Lanzhu and Mia Taylor, and her image color is jade green. She comes from the prestigious, wealthy Mifune family as the second daughter. In the game's narrative, she challenged Setsuna Yuki for the presidency due to dissatisfaction with her leadership, believing students should prioritize activities where they could succeed over merely pursuing passions. She vowed to disband the school idol club if elected. After being convinced by the club to try being a school idol herself, she eventually joined as its eleventh member and tenth school idol. In the anime adaptation, she appeared in the second season as a student council member who acted neutrally toward the idol club, occasionally assisting their activities. It was revealed her older sister, Kaoruko Mifune, was once a school idol, which initially inspired Shioriko's admiration. After her sister's group failed to reach the Love Live competition, Shioriko hid her interest due to a fear of failing herself. With encouragement from the club, she overcame her fears and became a school idol. Shioriko is calm, academically gifted, and pragmatic. She values Japanese traditions and has training in traditional dance and flower arranging. She can identify people's strengths and weaknesses, using this to offer constructive advice. In the game, her demeanor is often strict, cold, and antagonistic, though her suggestions ultimately help others succeed. Despite her reserved nature, she genuinely wants to help others and yearns for connection. The anime portrays her as genuinely kind, polite, and supportive from the beginning, even keeping secrets like Setsuna's dual identity. As student council president, she focuses on helping students succeed in their club activities. She spends spare time volunteering, such as interacting with children at a community center or cleaning the neighborhood. She is childhood friends with Zhong Lanzhu. Shioriko has semi-long dark green hair, vermilion eyes, and often wears a small yellow hair ribbon on the left side of her hair. She has a slim figure with specific measurements noted. Her given name means "bookmark" and "child," while her surname Mifune means "three" and "boat." She performs songs including "Sanketsu," "Eternalize Love!!," and "Doko ni Itemo Kimi wa Kimi."