Leyla Basticon commanded the Distonian Army Dimensional Dragoon Corps before joining the Babel Brigade. She despised humanity with profound hatred yet honored her former military subordinates. Her cold-blooded, serious nature enabled prolonged deception as a human, culminating in her revealing her true Disas form in Chapter 51.

Driven by vengeance for subordinates killed in the New York conflict—blamed squarely on Asuka Ootorii—Leyla framed her clash with Asuka as loyal retribution. She proved instrumental across the Babel Brigade’s campaigns: the Distonian War, Babel Brigade Arc, Okinawa Arc, Saving Phoenix Tamara Arc, and New York Arc. During the New York assault, she resurrected the Disas Beast, declaring it the revival of their "decapitated king" to unleash upon humanity, igniting a massive battle involving magical girls and human forces. In Chapter 52, Asuka publicly denounced Leyla’s actions via broadcast, dismissing her confidence as naive against the allies’ combined strength.

Leyla perished in Chapter 55, executed by Sayako Hata under Francine’s mental control during the Babel Brigade’s campaign climax. Her documented narrative remains confined to the main storyline, without significant extensions into spin-offs, movies, or other media.