Shirou Mizunuma holds the position of student council president at Konan Academy, spearheading efforts to protect the Latin Quarter clubhouse from demolition. Renowned for his sharp intellect and tactical mindset, he partners with Shun Kazama to orchestrate protests, strategize covert actions like banner displays, and mask strategic debates as choir rehearsals using the school anthem.

Acedemic excellence defines him, particularly in physics, where he consistently ranks first—though occasional near-perfect scores spark friction with his teachers. His family’s scholarly legacy is reinforced by an older sister in astrophysics. Over time, he bonds with Sora Matsuzaki, Umi’s younger sister, attending events together and cultivating camaraderie through shared experiences.

Sporting brown hair and rectangular glasses, Shirou favors practical clothing, often wearing Konan’s blue uniform or casual ensembles like a blue turtleneck and brown jeans. His demeanor balances relaxed charm with shrewd calculation, enabling him to defuse tensions and stay composed during crises. He openly expresses appreciation for Umi and fellow clubhouse renovation allies.

When advocating for the Latin Quarter, he joins Umi and Shun in Tokyo to negotiate with Chairman Tokumaru, employing diplomatic finesse to secure a pivotal meeting that advances their campaign. As a leader, he mobilizes suppliers and students to restore the clubhouse, overseeing repairs and cleanup efforts.

The name "Shirou" merges "history" and "son," reflecting his dedication to institutional heritage, while "Mizunuma" (water swamp) hints at adaptability and depth. His arc emphasizes a balance between collaborative leadership and self-reliance, uniting academic discipline with a passion for community-building and preserving collective memory.