In an attempt to protect the planet from alien invaders and their monstrous creatures, Dr. Kishida constructs a colossal robot, designed exclusively for the ultimate female warrior. However, his granddaughters decline the opportunity to pilot this machine, as they are too preoccupied with their own lives, including studying for their college entrance exams. Despite this setback, the invaders are also struggling, as the Earth they targeted for being peaceful, abundant and vulnerable has proven to be much more difficult to conquer than they initially presumed. With the Audit warning of the potential increase in costs and the arrival of the head of Galactic Headquarters to supervise operations, it remains uncertain whether they will trigger a brute force response. Now, the entire fate of the world is in the hands of Aya Kishida, the doctor’s granddaughter, who may have to abandon her studies to control ARIEL – the mighty and elegant robot, and Saber Starblast, a cryptic alien, who holds the power to vanquish the invaders for good.