Released as part of a Neo Action double bill with Tsujimoto Takanori's Hard Revenge, Milly, Kaneko Isao's The Masked Girl follows the giddy action adventures of a high school superheroine called upon to battle supreme evil. On the way home from school one day, high school girl Hoshino Ai (Shimizu Yuki) gets kidnapped by an evil crime organization called Joker, led by devil incarnate Black Maria (Sato Aiko). Ai manages to escape with the help of teacher Aoyama (Kida Tsuyoshi), but realizes she's gained superhero powers after being genetically modified by Joker. She reveals her problems to friend Yumi (Nakamura Shizuka), only to discover that Yumi also been genetically modified and brainwashed to serve Joker. Friends become foes as Ai is forced to fight Yumi, but that's only the beginning of the battle. To take down Black Maria and Joker, Ai must trade in her sailor skirt for superheroine threads, and become The Masked Girl!