Athletic high school girls are being abducted by a mysterious organization known as The Clown' that turns them into soulless super-soldiers in a bid to take over the world. Due to a mix-up, bumbling athlete Hoshino is abducted and given superpowers by The Clown, but is rescued from the facility by her gym teacher before 'brain wash surgery' can be performed to complete her transformation, and vows to battle the organization and its 'monster killers' to the very end . . . as The Masked Girl.