Mukyū Isurugi serves as a member of the antagonistic Revisions, distinguished by her dog-like ears, bushy tail, and vivid green hair trimmed at ear length, paired with piercing yellow eyes. Her temporary body, selected by the Revisions for human interaction, adopts a gothic lolita-inspired maid outfit—a design she unknowingly wears, oblivious to its fanservice intent.

Her demeanor leans toward sadism, marked by ruthless actions against Shibuya’s displaced inhabitants, yet she contrasts this cruelty with unwavering tenderness toward her twin sister, Chiharu Isurugi. Their bond anchors Mukyū’s morality, prioritizing familial loyalty above all else. Both sisters fervently believe their harsh methods are essential to fulfilling the Revisions’ objectives, framing their violence as a grim necessity for their faction’s survival.

In the Revisions’ hierarchy, Mukyū and Chiharu hold authority over Nicolas Satō, whom they command with harsh disdain, leveraging their superior status to enforce compliance. The twins’ animalistic traits and temporary bodies serve pragmatic roles in their missions, though their true forms and origins remain undisclosed. Mukyū’s actions consistently reflect her dual nature: a merciless enforcer of her faction’s will and a fiercely protective sibling. Her past remains undefined, with no elaboration on her origins or existence beyond her role in the central conflict.