Shizu Itō, a first-year student at Yurigaoka Girls Academy, commands the Schwarz-Grail Legion as its captain. Known as the "Ice Emperor" for her unmatched combat skills and unwavering composure, she employs a unique tactical style called "illusionism"—meticulously engineered maneuvers that emulate phantom-like agility on the battlefield.

Born into a family steeped in the legacy of a prominent financial conglomerate, her childhood was marked by a fractured household dynamic, fueling personal challenges throughout middle school. Her relationship with her younger sister, Naehi Itō, remains a strained yet intricate dynamic, characterized by Naehi’s silent admiration and emotional detachment.

Though initially drawn to freelance operations, Shizu’s philosophy transformed after a pivotal encounter with the Hitotsuyanagi team, whose collective resolve inspired her to forge her own legion. This shift underscores her growth as a leader dedicated to harnessing unity over individualism.

In combat, she brandishes a massive two-handed sword with masterful balance of brute force and calculated strikes. Her stoic exterior belies a fierce loyalty to her allies, frequently shielding them at personal risk. While her strategies prioritize disciplined logic, subtle glimpses of her quieter commitment to nurturing team trust surface in fleeting, purposeful interactions.